title: How to count multiple items in a list
body: <p>I have the following list:</p>
  
  <pre><code>data = [[2004,1,1,1,50], [2008,2,28,1,150],[1984,5,1,3,20],[1982,5,1,7,20], [1982,5,8,7,20]]
  </code></pre>
  
  <p>The data represents the Year, Month, Day, Day of week, count. </p>
  
  <p>I want to obtain a dictionary of the total counts per day of the week. Something like this </p>
  
  <pre><code>results = {1:200,
             2:0,
             3:20,
             4:0,
             5:0,
             6:0,
             7:40,
  }
  </code></pre>
  
  <p>I believe the best way to do this, please correct me if i'm wrong, is to use collections.Counter. I abandoned this effort for a dictionary comprehension but have been unable to solve the problem</p>
  
  <pre><code>solution = {(x,i) for x[3], i[4] in data}
  </code></pre>