本コンポーネントには、シリーズごとにデータラベルのフォーマット（小数点表示と％表示など）を変更する組み込みの機能は用意されていません。

代替方法として、SeriesクラスのSymbolRenderingイベントで、Graphics.DrawStringメソッドを使用して独自に文字列を描画する方法が考えられます。

以下に、簡単な設定コードを記載します。



◎サンプルコード（VB）

Imports C1.Chart
Imports C1.Win.Chart

Public Class Form1
    Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
        ' データの作成
        Dim dt As New DataTable()
        dt.Columns.AddRange(New DataColumn() {
            New DataColumn("X", GetType(Double)),
            New DataColumn("Y1", GetType(Double)),
            New DataColumn("Y2", GetType(Double))
        })

        dt.Rows.Add(1, 80, 0.6)
        dt.Rows.Add(2, 120, 0.8)
        dt.Rows.Add(3, 90, 0.7)
        dt.Rows.Add(4, 130, 0.9)
        dt.AcceptChanges()

        FlexChart1.Series.Clear()

        ' 系列の設定
        Dim series1 As New Series() With {
            .Name = "S1",
            .Binding = "Y1",
            .BindingX = "X",
            .ChartType = ChartType.Column,
            .AxisY = New Axis() With {
                .Position = Position.Left,
                .Format = "#,#",
                .Min = 0,
                .Max = 200,
                .Title = "S1"
            }
        }

        Dim series2 As New Series() With {
            .Name = "S2",
            .Binding = "Y2",
            .BindingX = "X",
            .ChartType = ChartType.LineSymbols,
            .AxisY = New Axis() With {
                .Position = Position.Right,
                .Format = "P1",
                .Min = 0,
                .Max = 1,
                .Title = "S2"
            }
        }

        FlexChart1.Series.Add(series1)
        FlexChart1.Series.Add(series2)

        ' FlexChartのデータバインド
        FlexChart1.DataSource = dt

        ' 独自のデータラベルの描画
        AddHandler series1.SymbolRendering, AddressOf seriesInt_SymbolRendering
        AddHandler series2.SymbolRendering, AddressOf seriesPct_SymbolRendering
    End Sub

    Private Sub seriesInt_SymbolRendering(sender As Object, e As RenderSymbolEventArgs)
        ' データラベルを独自に描画します
        Dim value As String = Convert.ToString(e.Series.GetValues(0)(e.Index))
        Dim textRect As SizeF = e.Graphics.MeasureString(value, Me.Font)
        Dim height As Single = CSng((FlexChart1.AxisY.Convert(0) - e.Point.Y) / 2 + e.Point.Y - textRect.Height / 2)
        Dim pos As New PointF(e.Point.X - textRect.Width / 2, e.Point.Y)
        Dim number As Integer = Integer.Parse(value)
        Dim formatted As String = number.ToString("N0")
        e.Graphics.DrawString(formatted, Me.Font, Brushes.DarkBlue, pos)
    End Sub

    Private Sub seriesPct_SymbolRendering(sender As Object, e As RenderSymbolEventArgs)
        ' データラベルを独自に描画します
        Dim value As String = Convert.ToString(e.Series.GetValues(0)(e.Index))
        Dim textRect As SizeF = e.Graphics.MeasureString(value, Me.Font)
        Dim height As Single = CSng((FlexChart1.AxisY.Convert(0) - e.Point.Y) / 2 + e.Point.Y - textRect.Height / 2)
        Dim pos As New PointF(e.Point.X - textRect.Width / 2, e.Point.Y - 25)
        Dim number As Double = Double.Parse(value)
        Dim formatted As String = number.ToString("P1")
        e.Graphics.DrawString(formatted, Me.Font, Brushes.Black, pos)
    End Sub
End Class

◎サンプルコード（C#）

using C1.Chart;
using C1.Win.Chart;

namespace prj_FlexChart
{
    public partial class Form1 : Form
    {
        int npts = 5;
        Random rnd = new Random();

        public Form1()
        {
            InitializeComponent();
        }

        private void Form1_Load(object sender, EventArgs e)
        {
            // データの作成
            DataTable dt = new DataTable();
            dt.Columns.AddRange(new DataColumn[]
            {
                new DataColumn("X", typeof(double)),
                new DataColumn("Y1", typeof(double)),
                new DataColumn("Y2", typeof(double)),
            });
            dt.Rows.Add(1, 80, 0.6);
            dt.Rows.Add(2, 120, 0.8);
            dt.Rows.Add(3, 90, 0.7);
            dt.Rows.Add(4, 130, 0.9);
            dt.AcceptChanges();

            flexChart1.Series.Clear();

            // 系列の設定
            var series1 = new Series()
            {
                Name = "S1",
                Binding = "Y1",
                BindingX = "X",
                ChartType = ChartType.Column,
                AxisY = new Axis()
                {
                    Position = Position.Left,
                    Format = "#,#",
                    Min = 0,
                    Max = 200,
                    Title = "S1"
                },
            };
            var series2 = new Series()
            {
                Name = "S2",
                Binding = "Y2",
                BindingX = "X",
                ChartType = ChartType.LineSymbols,
                     AxisY = new Axis()
                     {
                          Position = Position.Right,
                          Format = "P1",
                         Min = 0,
                         Max = 1,
                         Title = "S2"
                     },
            };
            flexChart1.Series.Add(series1);
            flexChart1.Series.Add(series2);

            // FlexChartのデータバインド
            flexChart1.DataSource = dt;

            // 独自のデータラベルの描画
            series1.SymbolRendering += seriesInt_SymbolRendering;
            series2.SymbolRendering += seriesPct_SymbolRendering;
        }

        private void seriesInt_SymbolRendering(object sender, RenderSymbolEventArgs e)
        {
            // データラベルを独自に描画します
            var value = Convert.ToString(e.Series.GetValues(0)[e.Index]);
            var textRect = e.Graphics.MeasureString(value, this.Font);
            var height = (float)(flexChart1.AxisY.Convert(0) - e.Point.Y) / 2 + e.Point.Y - textRect.Height / 2;
            var pos = new PointF(e.Point.X - textRect.Width / 2, e.Point.Y);
            int number = int.Parse(value);
            string formatted = number.ToString("N0");
            e.Graphics.DrawString(formatted, this.Font, Brushes.DarkBlue, pos);
        }

        private void seriesPct_SymbolRendering(object sender, RenderSymbolEventArgs e)
        {
            // データラベルを独自に描画します
            var value = Convert.ToString(e.Series.GetValues(0)[e.Index]);
            var textRect = e.Graphics.MeasureString(value, this.Font);
            var height = (float)(flexChart1.AxisY.Convert(0) - e.Point.Y) / 2 + e.Point.Y - textRect.Height / 2;
            var pos = new PointF(e.Point.X - textRect.Width / 2, e.Point.Y - 25);
            double number = double.Parse(value);
            string formatted = number.ToString("P1");
            e.Graphics.DrawString(formatted, this.Font, Brushes.Black, pos);
        }
    }
}