How do I create a dynamic 100% stacked column chart using VBA?

Question

I have a macro which updates a cluster column chart when values are entered in the range start and range end cells. I would like to edit this VBA code to instead create a 100% stacked column chart. How do I do this?? See example of current code below:

Sheets("Inputs1").Select
'ActiveSheet.Inputs1.Select
Range("A4").Select
RangeStart = Selection
Range("B4").Select
RangeEnd = Selection

Application.ScreenUpdating = False


'Update Chart Unique Visitors
Sheets("Monthly SuperMetrics Data").Select
Cells(4, 1).Select
Do Until Selection = ""
    If Selection = "Unique Visitors (A)" Then
    varRow = ActiveCell.Row
    End If
Selection.Offset(1, 0).Select
Loop
stringvariable = Trim(Str(varRow))
ChartRange = RangeStart + "3:" + RangeEnd + "3," + RangeStart + stringvariable + ":" + RangeEnd + stringvariable
Sheets("SuperMetrics Graphing").Select
ActiveSheet.ChartObjects("Chart_Unique_Visitors").Activate
ActiveChart.ChartArea.Select
ActiveChart.ChartType = xlColumnClustered
ActiveChart.SetSourceData Source:=Sheets("Monthly SuperMetrics Data").Range(ChartRange), PlotBy:=xlRows
ActiveChart.Location Where:=xlLocationAsObject, Name:= _
    "SuperMetrics Graphing"
ActiveChart.HasDataTable = False