title: how to show 2 lines with different range on nvd3 graph
body: <p>I am plotting a line graph using nvd3 library, it plots two lines but there is huge difference in both line values, one line (line 1) have values close to 500 and second line (line 2) have values between 0-1 because of range difference line 2 which have values in 0-1 is shown as flat line close to x-axis though its values are changing.</p>
  
  <p>If I hide line 1 than i see the line 2 properly with variations, how can I show this kind of graph, here is the code and some snap shots :</p>
  
  <pre><code>nv.addGraph(function() {
        var chart = nv.models.lineChart()
                      .width(800).height(420)
                      .margin({left: 100,right:100})  //Adjust chart margins to give the x-axis some breathing room.
                      .useInteractiveGuideline(true)  //We want nice looking tooltips and a guideline!
                      .transitionDuration(350)  //how fast do you want the lines to transition?
                      .showLegend(true)       //Show the legend, allowing users to turn on/off line series.
                      .showYAxis(true)        //Show the y-axis
                      .showXAxis(true)        //Show the x-axis
        ;
  
  
    chart.xAxis     //Chart x-axis settings
        .axisLabel('X-axis');
  
    chart.yAxis     //Chart y-axis settings
        .axisLabel('')
        .tickFormat(d3.format('.02f'));
  
  
    d3.select('#graph-chart svg')    //Select the &lt;svg&gt; element you want to render the chart in.   
        .datum(data)        //Populate the &lt;svg&gt; element with chart data...
        .call(chart);          //Finally, render the chart!
  
    //Update the chart when window resizes.
    nv.utils.windowResize(function() { chart.update(); });
    return chart;
  });
  </code></pre>
  
  <p>Graph with both values here beta is shown as flat line :</p>
  
  <p><img src="https://i.stack.imgur.com/yLkFc.png" alt="enter image description here"></p>
  
  <p>Graph only with beta :</p>
  
  <p><img src="https://i.stack.imgur.com/ZUVSS.png" alt="enter image description here"></p>
  
  <p>Edit :</p>
  
  <p>Testing data</p>
  
  <pre><code> {
      "key": "key1",
      "values": [
          [
              1697000000,
              19024000000
          ],
          [
              1764000000,
              19764000000
          ],
          [
              1829000000,
              21496000000
          ],
          [
              2122000000,
              20559000000
          ]
      ]
  },
  {
      "key": "key2",
      "values": [
          [
              1697000000,
              13530000
          ],
          [
              1764000000,
              41790000
          ],
          [
              1829000000,
              29280000
          ],
          [
              2122000000,
              11050000
          ]
      ]
  }
  </code></pre>