charts_flutter show numbers under 0

hello i want to show a cryptocurrency chart but the values are under 0 like 000006696077577877439 the chart dont show me any data because is 0

final simpleCurrencyFormatter =
new charts.BasicNumericTickFormatterSpec.fromNumberFormat(
    new NumberFormat.decimalPercentPattern(decimalDigits: 21));

  static List<charts.Series<MyRow, DateTime>> _createSampleData() {
    final data = [
      new MyRow(new DateTime(2017, 9, 25), 0.000003230355922409315),
      new MyRow(new DateTime(2017, 9, 26), 0.000005566276534775064),
      new MyRow(new DateTime(2017, 9, 27),0.000006696077577877439),
      new MyRow(new DateTime(2017, 9, 28), 0.000006850531948490849),
      new MyRow(new DateTime(2017, 9, 29), 0.000006850531948490849),

    ];

    return [
      new charts.Series<MyRow, DateTime>(
        id: 'Cost',
        domainFn: (MyRow row, _) => row.timeStamp,
        measureFn: (MyRow row, _) => row.cost,
        data: data,

      )
    ];
  }