title: How to split list of dates into weeks
body: <p>I have a list of dates, that range from July 2015 to January 2016</p>
  
  <pre>
  2015/07/20 14:15:23 
  2015/07/20 14:16:06 
  2015/07/26 23:39:15 
  2015/09/02 22:51:46 
  2015/09/02 22:52:33 
  2015/10/26 20:42:23 
  2015/11/12 14:54:31 
  2015/11/30 06:49:10 
  2015/12/02 10:18:17 
  2015/12/10 08:34:53 
  2015/12/10 15:15:33 
  2015/12/15 06:43:32 
  2015/12/29 02:55:01 
  2016/01/12 19:46:45 
  2016/01/13 07:31:14 
  2016/01/13 07:32:59 
  2016/01/14 05:28:33 
  </pre>
  
  <p>I want to split these up into weeks, So I know exactly how many weeks have passed by and get a count for each group. I'm pulling the dates from a webservice and putting them into a datagridview. </p>
  
  <p>I'm going to add a column called week, where I cant to add the week each belongs to.</p>
  
  <pre><code>if (SplitChkBox.Checked == true)
  {
      column = new DataColumn();
      column.DataType = System.Type.GetType("System.String");
      column.ColumnName = "Week";
      table.Columns.Add(column);
  }
  </code></pre>
  
  <p>Eventually I'll create a graph off how many instances belong to each week.</p>
  
  <p>Thanks!</p>
  
  <p><strong>EDIT</strong></p>
  
  <p>From <code>2015/07/20</code> there are about 25 weeks until <code>2016/01/14</code>. I want to return 1-25 and the count of how many weeks belong to that group if its more than 0.</p>