title: display every other item on axis
body: <p>Google line chart displaying temperature hour for hour. Is it possible to just display every other hour on the x-axis. I could just set every second string to <code>empty</code>, but then one wouldn't be able to display it when hovering over the graph.</p>
  <p>Maybe you could do something here?:</p>
  <pre><code>var options = {
   hAxis: {
   format: ''
   }
  }
  </code></pre>