title: Python counting occurrence of values in dictionary
body: <p>I'm trying to calculate the occurrence of countries in a dictionary.
  I am reading all country`s with a for loop from a CSV file. And add them to a list:</p>
  
  <pre><code>landen = []
  landen.append({"Datum": datumbestand, "Land": [land]})
  </code></pre>
  
  <p>Then I try to combine all countries by date:</p>
  
  <pre><code>scores_unique = {}
  for item in landen:
      if item['Datum'] not in scores_unique:
          scores_unique.update({item['Datum']: item['Land']})
      else:
          scores_unique[item['Datum']] += item['Land']
  </code></pre>
  
  <p>When I print my output I get the following (A little part of my data):</p>
  
  <pre><code>[('2017-11-20', [US', 'US', 'US', 'US', 'SK', 'SK', 'IE', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'GB', 'ES', 'ES', 'DE', 'CA', 'CA', 'CA', 'CA', 'CA', 'CA', 'CA', 'CA', 'CA', 'CA', 
  ('2017-11-10', ['US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US', 'US',
  </code></pre>
  
  <p>Now I would like to see from every date the countries who are most occurrence. Something like:</p>
  
  <pre><code>2017-11-20:
  USA 10x
  SK 3x
  IE 2x
  
  2017-11-10
  USA 20x
  GB 15x
  </code></pre>
  
  <p>And see the diffrence in occurence from every date. But I been trying a long time but I cant manage to count the occurence and print it.</p>