c3.generate({
  bindto: PANEL,
  data: {
    x: HEADERS[0],
    columns: COLUMNS,
    groups: [HEADERS.splice(1)],
    type: 'area'
  },
  axis: {
    x: {
      type: 'category',
      categories: COLUMNS[0],
      tick: {
        culling: true
      }
    }
  }
});