title: Google Combo Chart add horizontal and vertical line in column chart
body: <p>How do I create a Google Combo Chart that replicates the image below? It seems once I add the column for the vertical line the green columns lose their groupWidth property and turn into skinny lines.</p>
  
  <pre><code>    data.addColumn('number', 'X');
      data.addColumn('number', 'Y');
      data.addColumn('number', 'Average');
      data.addColumn('number', 'Vertical Line');
  
      data.addRows([
          [1, 5, 3, null],
          [3, 4, 3, null],
          [5, 2, 3, null],
          [2, null, null, 0], // add vertical line
          [2, null, null, 5],
      ]);
  </code></pre>
  
  <p>Here is a jsfiddle: <a href="http://jsfiddle.net/vmb4odkt/" rel="nofollow noreferrer">http://jsfiddle.net/vmb4odkt/</a></p>
  
  <p><img src="https://i.stack.imgur.com/OzQhB.jpg" alt="enter image description here"></p>