Vba code for target range of days

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I have the following vba code to specify days from an EndDate. How do I specify a target row for it to automatically insert when the EndDate is inserted? The EndDate will be in column D and the days will be in column E. Thanks

Function GetWorkDays(StartDate As Long, EndDate As Long) As Long
' returns the count of days between StartDate - EndDate minus Saturdays and Sundays
Dim d As Long, dCount As Long
    For d = StartDate To EndDate
        If WeekDay(d, vbMonday) < 6 Then
            dCount = dCount + 1
        End If
    Next d
    GetWorkDays = dCount
End Function