title: angular-nvd3 content percentage in tooltip
body: <p>I am looking into ways I can display the percent of a slice of pie compared to the current graph in the tooltip. </p>
  
  <p>First I tried looking for something similar to <code>chart.labelType: 'percent'</code> but it looks like there is no such option.</p>
  
  <p>What I am trying to do now is calculate the percentage inside <code>chart.tooltip.contentGenerator</code> according to documentation the function should be passed 5 arguments <code>function (key, x, y, e, series) -&gt; String</code> however I am only receiving the first argument.</p>
  
  <p>I am using angular 1.5.0, d3 3.5.16, nvd3 1.8.2, and angular-nvd3 1.0.5. </p>
  
  <p>What is the best practice for displaying the percentage in the tooltip?</p>