System.Web.UI.DataVisualization.Charting.ChartTypes.StackedAreaChart.GetYValue(System.Web.UI.DataVisualization.Charting.CommonElements, System.Web.UI.DataVisualization.Charting.ChartArea, System.Web.UI.DataVisualization.Charting.Series, System.Web.UI.DataVisualization.Charting.DataPoint, System.Int32, System.Int32)