title: Group list by month
body: <p>I have list with datetime objects. I would like to group by month and add it to the dictionary. </p>
  
  <p>So after grouping process I want to have list per month and year. 
  For example:
  Before grouping
  [mix below elements]</p>
  
  <p>After grouping:
  1) January 2015 - 5 elements
  2) February 2015 - 2 elements
  2) January 2014 - 2 elements</p>
  
  <p>I have tried like this:</p>
  
  <pre><code>var test = this.myList.GroupBy(x =&gt; x.myDate.Month).ToList();
  </code></pre>
  
  <p>But iI thnink I need to use dictionary. Do you have any ideas how to solve it ?</p>