title: Highcharts - Wrong date in tooltip
body: <p>fiddle -  <a href="http://jsfiddle.net/z8fw7/" rel="nofollow noreferrer">http://jsfiddle.net/z8fw7/</a></p>
  
  <p>When I hover over the column I can see this weird big number, where is it coming from.</p>
  
  <p><a href="https://imgur.com/d0h3p6y" rel="nofollow noreferrer"><img src="https://i.imgur.com/d0h3p6yl.png" title="Hosted by imgur.com"/></a></p>
  
  <p>If I add one more date entry. e.g</p>
  
  <pre><code>    [Date.UTC(2010,2,31), 28.84], 
      [Date.UTC(2011,2,31), 28.84], 
      [Date.UTC(2012,2,31), 32.65]
  </code></pre>
  
  <p>The tooltip then displays the proper year value as expected. It works flawlessly with 3 data values while it does not work with 2 data values. How can I make sure that it works with even 2 data values.</p>