title: highcharts stacked area with irregular x-intervals
body: <p>After a couple of weeks working with Highcharts, we are facing problems to generate charts that fit to out data structure. Would be nice if somebody can give us a hint.   </p>
  
  <p>Here is the problem:  </p>
  
  <ul>
  <li>We want to create a stacked area chart for 2 or more series.</li>
  <li>Since our x-values have irregular intervals we tried to set up value pairs for each data point [x,y]</li>
  </ul>
  
  <p>However, the area chart does not stack our y-values. Any suggestions?</p>
  
  <p>Here is an example of our problem: <a href="http://jsfiddle.net/FX7XE/1/" rel="nofollow">link to jsFiddle</a></p>
  
  <p>Thanks for your help!</p>
  
  <pre><code>$(function () {
      $('#container').highcharts({
          chart: {
              type: 'area'
          },
          title: {
              text: 'Irregular point intervalls stacked area'
          },
          yAxis: {
              title: {
                  text: 'value'
              }
          },
          plotOptions: {
              area: {
                  dataLabels: {
                      enabled: true
                  },
                  stacked: 'normal'
              }
          },
          series: [{
              name: 'test 1',
              data: [[0, 7.0], [1, 6.9], [1.5, 9.5], [3, 14.5]]
          }, {
              name: 'test 2',
              data: [[0, 3.9],[1, 4.2], [1.5, 5.7], [3, 8.5]]
          }]
      });
  });
  </code></pre>