    type : 'hour',
        count : 1,
        text : '1h'
      }, {
        type : 'all',
        count : 1,
        text : 'All'
      }
    ],
    selected : 3,
    inputEnabled : false
  },
  plotOptions: {
    series: {
      dataGrouping: { enabled: false }
    },
    area: {
      stacking: 'normal'
    }
  },
  xAxis: {
    type: 'datetime',
    ordinal: false,
    maxZoom: 10000 // three days
  },
  yAxis:[
    {
      min: 0,
      title: { text: 'Number of responses' },
      opposite: false,
   