title: Bar with negative and neutral stack
body: <p>I would like to display answers of type "yes/no/don't know". I was thinking about something similair to Bar with negative stack, but with "don't know" as a neutral part in the middle with equal width on both sides of zero. To show what I mean I added two neutral series to the standard fiddle. How can I merge them into one neutral series in the middle?</p>
  
  <pre><code>{
          name: 'Neutral',
          data: [...]
  }
  </code></pre>
  
  <p>Maybe I'm on the completely wrong track. Any suggestions?</p>
  
  <p><a href="http://jsfiddle.net/burktelefon/3jn0mLs9/" rel="nofollow noreferrer">modified Bar with negative stack-fiddle</a></p>