用Sliverlight 在中国地图每个省份上加饼图显示省下城市

<charts:Chart.Series>
                        <charts:DataSeries RenderAs="Pie" DataSource="{Binding ChartSource}">
                            <charts:DataSeries.DataMappings>
                                <charts:DataMapping MemberName="YValue" Path="YValue"></charts:DataMapping>
                                <charts:DataMapping MemberName="ToolTipText" Path="ToolTipText"></charts:DataMapping>
                                <charts:DataMapping MemberName="LabelText" Path="Description"></charts:DataMapping>
                            </charts:DataSeries.DataMappings>
                        </charts:DataSeries>

饼图显示 怎么后台添加饼图？