ecify the values you
   * need and the rest will be given sensible defaults as shown:
   *
   * <pre>
   * {
   *   minValue: undefined,                      // specify to clamp the lower y-axis to a given value
   *   maxValue: undefined,                      // specify to clamp the upper y-axis to a given value
   *   maxValueScale: 1,                         // allows proportional padding to be added above the chart. for 10% padding, specify 1.1.
   *   minValueScale: 1,                         // allows