title: Show daily count of zero when there are no records for a "group"
body: <p>I'm doing a daily count of errors grouped by type.  How would I make Day 2 show error2 with zero if there are no records with error2 on day 2?  </p>
  
  <p>Day 1</p>
  
  <pre><code>Type   Count
  error1   5
  error2   6
  error3   1
  </code></pre>
  
  <p>Day 2</p>
  
  <pre><code>type   Count
  error1   6
  error3   2
  </code></pre>