Sub Test()
Dim ar As Range
ls = 20
lr = Cells(Rows.Count, "A").End(xlUp).Row
For i = 1 To lr
If i Mod 24 = 0 Then Cells(i, 20) = "x"
Next i
For Each ar In Columns(20).SpecialCells(2).Areas
Debug.Print ar.Address
Rows(ar.Row + 1).EntireRow.Insert
Next ar
R2:
For Each ar In Columns("I").SpecialCells(2, 1).Areas
ar.Offset(0, 4) = WorksheetFunction.Average(ar)
ar.Offset(0, 5).FormulaR1C1 = "=RC[-5] / rC[-1]"
ar.Offset(0, 6) = WorksheetFunction.StDev_S(ar)
Range(Split(ar.Offset(1, 6).Address, ":")(1)).FormulaR1C1 = WorksheetFunction.StDev_S(ar)
Range(Split(ar.Offset(1, 7).Address, ":")(1)).FormulaR1C1 = "=RC[-1]/R[-1]C[-3]"
Next ar
End Sub