text: 
  $(function () {
      var formatter = d3.format('%');
  
      Contour.export('donutTextOneValue', function (data, layer, options) {
  
          // This visualization is only for single-element gauges, that is,
          // donut (pie) charts with one data series, one value visible, and the remainder dimmed out.
          // So we can assume that there are only two elements in the data series.
          var visibleIndex = data[0].data[0].y < data[0].data[1].y ? 1 : 0;
          var centerX = options.chart.plotWidth / 2;
          var centerY = options.chart.plotHeight / 2;
  
          layer.append('text')
              .attr('class', 'center-text')
              .attr('x', centerX)
              .attr('y', centerY)
              .attr('dy', '.3em')
              .text(formatter(data[0].data[visibleIndex].y));
  
          layer.append('text')
              .attr('class', 'center-label')
              .attr('x', centerX)
              .attr('y', centerY)
              .attr('dy', '2.3em')
              .text('Growth Rate');
      });
  
      var data = [{ x: 'Case A', y: 0.82}, { x: 'Case B', y: 0.18 }];
  
      new Contour({
              el: '.pie-gauge',
              pie: {
                  innerRadius: 90
              },
              tooltip: {
                  formatter: function(d) {
                      return d.data.x + ': ' + formatter(d.data.y);
                  }
              }
          })
          .pie(data)
          .donutTextOneValue(data)
          .render();
  });
  
  