title: Combining two dataframes into one dataframe w/ condtional
body: <p>I'm trying to calculate the crime rate per 100,000 population using values from two separate pivot table dataframes. </p>
  
  <pre><code>Crime Total
  
  Year                   2010    2011    2012    2013    2014    2015    2016
  CountyName                                                                 
  Alameda               12115   11971   13412   12327   10944   10463   11410
  Alpine                  355     481     200     174     125     202     165
  Amador                 2572    3033    2525    2390    2087    1856    2064
  Butte                  5966    5988    5459    5533    5085    6542    6324
  Calaveras              3236    4606    4586    4162    4055    3276    3012
  Colusa                 1219    1325    1322    1406     817     763     850
  Contra Costa            966    1032    1100     857     759     775    7553
  Del Norte              1923    2388    2229    1791    2140    2190    2048
  El Dorado             10259   11126   10305   10173    9938    9956   10394
  Fresno                  688     654     698     803     470     693   20858
  Glenn                   841     769    1130    1862    1203     876     775
  Humboldt               7087    5684    5428    5649    4582    4278    4308
  Imperial               3805    3405    4011    3930    3453    3658    2706
  Inyo                    833     858    1061     999     997     697    1061
  Kern                  52636   52164   59685   55531   47718   51277   54088
  Kings                  3161    3573    3056    3309    2396    2450    2413
  Lake                   5117    4123    4646    4655    4086    4265    3296
  Lassen                  767     837    1021     969    1019    1130    1104
  Los Angeles               4      11       0       5      24       4   96929
  Madera                 6620    8080    8179    6855    6243    6395    6058
  Marin                  4112    3768    3630    3531    3092    3550    3412
  Mariposa               1502    1796    1749    1651    1495    1572    1284
  Mendocino              3714    3589    3633    4076    3634    3245    3523
  Merced                11111   12008   10650    9678    8123    8189    8423
  Modoc                   313     506     506     584     402     394     270
  Mono                    392     353     314     362     362     252     309
  Monterey               6734    6635    6645    6973    6964    6366    7023
  Napa                   2021    1898    1779    1896     570     438    1478
  Nevada                 3031    2984    3632    3801    3096    3629    3261
  Orange                 6309    6645    7035    6328    6178    6410    5618
  Placer                10059   10132    8756    9256    8560    8912    8151
  Plumas                 1990    2011    2198    1985    1604    1492    1928
  Riverside             46050   39713   36571   34312   30229   34105   33843
  Sacramento            12848   12649   14790   13039   13045   14709   53793
  San Benito             1620    1273    1320    1048    1153     888     679
  San Bernardino        28350   31145   31297   29480   25899   27084   24922
  San Diego             31015   30472   34700   30709   26191   25877   25908
  San Francisco        158588  158741  182747  228175  213410  242800  219601
  San Joaquin           22005   23620   22615   20859   19080   18623   16330
  San Luis Obispo         397     324     603    1200    1283    1479    7646
  San Mateo              8060    9019   11958   13008   11485   13037   13387
  Santa Barbara          8106    8173    9627    9264    8338    8685    8338
  Santa Clara            8588    7139    8256    7130    6463    6646    6844
  Santa Cruz            10786   11383    9439    9563    8847    9566    9902
  Shasta                 7440    6922    7022    6823    6748    7777    6964
  Sierra                  333     270     274     358     167     145     170
  Siskiyou               1250    1390    1068    1034    1027     953    1296
  Solano                  751    2242    2341    2263    2127    2210    1719
  Sonoma                 9203    8420    9413    9080    9203    9869    9265
  Stanislaus            13995   11303   11431   11763   10183   10646    9535
  Sutter                 3352    3989    3548    4067    3020    2732    2927
  Tehama                 2094    2268    2276    2059    1858    2072    2552
  Trinity                 663     668     861     705    1095    1316    1762
  Tulare                15447   16816   15865   14896   10830   10775   10835
  Tuolumne               3734    3706    3974    3938    3491    4162    3989
  Ventura                6411    5406    5766    4885    4230    4351    3970
  Yolo                   1801    2079    2257    1930    1516    1656    1364
  Yuba                   5263    6836    6819    6736    6812    6210    5442
  
      Population Total
  
  Year                        2010        2011        2012        2013        2014        2015        2016
  CountyName                                                                                              
  Alameda                1510271.0   1525695.0   1543027.0   1567091.0   1588348.0   1611318.0   1629233.0
  Alpine                    1175.0      1169.0      1166.0      1164.0      1163.0      1163.0      1160.0
  Amador                   38091.0     38011.0     37945.0     37304.0     37815.0     37764.0     37667.0
  Butte                   220000.0    220828.0    221064.0    222341.0    223301.0    224467.0    224703.0
  Calaveras                45578.0     45557.0     45495.0     45424.0     45358.0     45266.0     45246.0
  California            37253956.0  37536835.0  37881357.0  38238492.0  38572211.0  38915880.0  39189035.0
  Colusa                   21419.0     21521.0     21597.0     21698.0     21794.0     21873.0     21965.0
  Contra Costa           1049025.0   1059495.0   1069977.0   1083721.0   1097644.0   1111899.0   1126824.0
  Del Norte                28610.0     28235.0     28066.0     27800.0     27357.0     26992.0     27006.0
  El Dorado               181058.0    181170.0    180952.0    180720.0    181977.0    183100.0    184371.0
  Fresno                  930450.0    938524.0    947615.0    956098.0    964757.0    975324.0    985079.0
  Glenn                    28122.0     28238.0     28317.0     28424.0     28497.0     28564.0     28639.0
  Humboldt                134623.0    135711.0    135289.0    135081.0    135059.0    135247.0    135557.0
  Imperial                174528.0    176370.0    178973.0    180224.0    181989.0    184624.0    186080.0
  Inyo                     18546.0     18536.0     18559.0     18557.0     18613.0     18563.0     18632.0
  Kern                    839631.0    845978.0    854122.0    864061.0    872123.0    880664.0    886803.0
  Kings                   152982.0    151322.0    151330.0    150440.0    149732.0    149704.0    149822.0
  Lake                     64665.0     64491.0     64347.0     64749.0     64835.0     65170.0     64790.0
  Lassen                   34895.0     34485.0     33735.0     32812.0     31993.0     31613.0     30841.0
  Los Angeles            9818605.0   9874887.0   9956722.0  10021318.0  10089847.0  10150617.0  10182961.0
  Madera                  150865.0    151256.0    151423.0    151377.0    153258.0    154857.0    154933.0
  Marin                   252409.0    253964.0    255812.0    257420.0    260554.0    262305.0    263150.0
  Mariposa                 18251.0     18251.0     18238.0     18195.0     18218.0     18172.0     18167.0
  Mendocino                87841.0     87436.0     87634.0     88227.0     88232.0     88278.0     88771.0
  Merced                  255793.0    258852.0    262147.0    264437.0    266556.0    269132.0    271547.0
  Modoc                     9686.0      9696.0      9670.0      9646.0      9636.0      9617.0      9620.0
  Mono                     14202.0     14219.0     14191.0     14059.0     13942.0     13851.0     13654.0
  Monterey                415057.0    417894.0    423166.0    427087.0    429298.0    432664.0    438171.0
  Napa                    136484.0    136913.0    138074.0    138867.0    140263.0    140992.0    141888.0
  Nevada                   98764.0     98409.0     98069.0     97848.0     97927.0     98315.0     98609.0
  Orange                 3010232.0   3035167.0   3069454.0   3102606.0   3127083.0   3152376.0   3172152.0
  Placer                  348432.0    353228.0    358152.0    362551.0    367442.0    370710.0    376203.0
  Plumas                   20007.0     19983.0     19967.0     19920.0     19893.0     19860.0     19837.0
  Riverside              2189641.0   2212874.0   2239715.0   2266290.0   2291699.0   2318762.0   2348213.0
  Sacramento             1418788.0   1429653.0   1440456.0   1452994.0   1466309.0   1482542.0   1496619.0
  San Benito               55269.0     55524.0     55781.0     55998.0     56219.0     56451.0     56621.0
  San Bernardino         2035210.0   2054735.0   2070374.0   2086576.0   2101525.0   2122015.0   2135724.0
  San Diego              3095313.0   3120688.0   3153951.0   3195215.0   3231651.0   3266192.0   3286717.0
  San Francisco           805235.0    815854.0    826103.0    839242.0    848022.0    857410.0    864889.0
  San Joaquin             685306.0    691818.0    698412.0    704727.0    712046.0    723985.0    735677.0
  San Luis Obispo         269637.0    270057.0    271348.0    273417.0    275762.0    276862.0    278480.0
  San Mateo               718451.0    726305.0    735256.0    745639.0    752355.0    759609.0    765895.0
  Santa Barbara           423895.0    424610.0    428584.0    433117.0    438578.0    443143.0    447295.0
  Santa Clara            1781642.0   1803362.0   1828496.0   1856416.0   1879196.0   1903209.0   1922619.0
  Santa Cruz              262382.0    264761.0    266918.0    269120.0    271061.0    273856.0    275557.0
  Shasta                  177223.0    177694.0    177693.0    178661.0    179067.0    179312.0    178232.0
  Sierra                    3240.0      3234.0      3233.0      3215.0      3204.0      3195.0      3194.0
  Siskiyou                 44900.0     44854.0     44841.0     44825.0     44809.0     44730.0     44722.0
  Solano                  413344.0    413438.0    415862.0    419185.0    423283.0    427122.0    430972.0
  Sonoma                  483878.0    485417.0    487487.0    491993.0    495798.0    500051.0    502604.0
  Stanislaus              514453.0    517748.0    521620.0    525845.0    529994.0    535125.0    541466.0
  Sutter                   94737.0     95591.0     95948.0     95722.0     96036.0     96390.0     96614.0
  Tehama                   63463.0     63531.0     63584.0     63641.0     63743.0     63837.0     63942.0
  Trinity                  13786.0     13758.0     13742.0     13731.0     13722.0     13676.0     13647.0
  Tulare                  442179.0    445662.0    450672.0    455091.0    458840.0    462061.0    466563.0
  Tuolumne                 55365.0     55309.0     55249.0     54938.0     55082.0     54663.0     54949.0
  Ventura                 823318.0    829511.0    834253.0    840955.0    847103.0    851451.0    853893.0
  Yolo                    200849.0    202836.0    204578.0    207329.0    208957.0    211126.0    215522.0
  Yuba                     72155.0     72520.0     72906.0     73343.0     73646.0     74044.0     74328.0`
  </code></pre>
  
  <p>I would like to combine the values in each column using the equation: </p>
  
  <p><strong>Crime Rate = (Total Crime / Total Population) x 100,000</strong></p>
  
  <p>Then place the crime rate in a new pivot table dataframe with index = CountyName, columns = Year, and values = crime rate per 100,000 population. </p>
  
  <p><strong>Crime and Population Pivot Table Index:</strong></p>
  
  <pre><code>Index(['Alameda', 'Alpine', 'Amador', 'Butte', 'Calaveras', 'Colusa', 'Contra Costa', 'Del Norte', 'El Dorado', 'Fresno', 'Glenn', 'Humboldt', 'Imperial', 'Inyo', 'Kern', 'Kings', 'Lake', 'Lassen', 'Los Angeles', 'Madera', 'Marin', 'Mariposa', 'Mendocino', 'Merced', 'Modoc', 'Mono', 'Monterey', 'Napa', 'Nevada', 'Orange', 'Placer', 'Plumas', 'Riverside', 'Sacramento', 'San Benito', 'San Bernardino', 'San Diego', 'San Francisco', 'San Joaquin', 'San Luis Obispo', 'San Mateo', 'Santa Barbara', 'Santa Clara', 'Santa Cruz', 'Shasta', 'Sierra', 'Siskiyou', 'Solano', 'Sonoma', 'Stanislaus', 'Sutter', 'Tehama', 'Trinity', 'Tulare', 'Tuolumne', 'Ventura', 'Yolo', 'Yuba'], dtype='object', name='CountyName')
  </code></pre>