excel vba combobox hide/show sheets (test 2)

Private Sub DropDown2_Initialize()
    Me.DropDown2.AddItem ("all")
    With DropDown2
        Dim year_counter As Integer
        For year_counter = 2012 To 2025
            .AddItem (year_counter)
        Next year_counter
    End With
End Sub


Sub DropDown2_Change()

    Call hideAllMonthlySheets

        If DropDown2.Value = "all" Then
            Call showAllMonthlySheets
        ElseIf DropDown2.Value > 2000 Then
            For month_counter = 1 To 12
               Sheets("subtotals-" + DropDown2.Value + "-" + month_counter).Visible = xlSheetVisible
            Next month_counter
       End If

    End With
End Sub

Sub showAllMonthlySheets()
    Dim year_counter As Integer
    For year_counter = 2012 To 2025
        Dim month_counter As Integer
        For month_counter = 1 To 12
            Sheets("subtotals-" + year_counter + "-" + month_counter).Visible = xlSheetVisible
        Next month_counter
    Next year_counter
End Sub


Sub hideAllMonthlySheets()
    For year_counter = 2012 To 2025
        For month_counter = 1 To 12
            Sheets("subtotals-" + DropDown2.Value + "-" + month_counter).Visible = xlSheetHidden
        Next month_counter
    Next year_counter

End Sub