title: Access last index value of dataframe
body: <p>I have an example dataframe (df) for 2 products:</p>
  
  <pre><code>                         BBG.XAMS.FUR.S               BBG.XAMS.MT.S
  date                                                               
  2014-10-23                 -2368.850388                    0.000000
  2014-10-24                  6043.456178                    0.000000
  2015-03-23                    -0.674996                   -0.674997
  2015-03-24                    82.704951                   11.868748
  2015-03-25                   -11.027327                   84.160210
  </code></pre>
  
  <p>Is there a way to retrieve the last index value of a dataframe only.  So in this example the date value I need retrieved is 2015-03-25?</p>