title: Highcharts bar: height by xAxis
body: <p>Have bar chart with many many entries on xAxis. But they are too close to each other.
  Example: <a href="http://jsfiddle.net/XUsCq/" rel="nofollow">http://jsfiddle.net/XUsCq/</a></p>
  
  <pre><code>    xAxis: {
          categories: ['Africa', 'America', 'Asia', 'Europe', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania', 'Oceania'],
          title: {
              text: null
          }
      },
  </code></pre>