Private Sub CommandButton1_Click()
Dim i As Long
Application.ScreenUpdating = False
For i = Cells(Rows.Count, 1).End(xlUp).Row + 1 To 2 Step -7
Rows(i).Insert Shift:=xlDown
Cells(i, 1) = "Moyenne"
Range(Cells(i, 3), Cells(i, 12)).FormulaLocal = "=MOYENNE(C" & i - 1 & ":C" & i - 7 & ")"
Next i
Application.ScreenUpdating = True
End Sub