title: dc.js month chart uneven spacing between bars
body: <p>I am creating a chart using dc.js and as you can see the spacing between the months are different. The most notable is between February and March because February only has 28 days. How do I have even spacing between the months?</p>
  
  <pre><code>           chart
                  //dimensions
                  .height(250)
                  .margins({top: 10, right: 50, bottom: 25, left: 50})
                  //x-axis
                  .x(d3.time.scale().domain(domain))
                  .round(d3.time.month.round)
                  .xUnits(d3.time.months)
                  .elasticX(true)
                  .xAxisPadding(20)
                  //left y-axis
                  .yAxisLabel('Dollars')
                  .elasticY(true)
                  .renderHorizontalGridLines(true)
                  // right y-axis
                  .rightYAxisLabel('Quantity')
                  //composition
                  .compose(composition)
  
                  .brushOn(false)
                  .xAxis().tickFormat(d3.time.format('%b %y'));
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/fngdZ.png" alt="Chart"></p>