Private Sub Summe_Spalten()
        Dim summe As Decimal = 0
        For i As Integer = 0 To DGV_Winter.Rows.Count - 1
            If DGV_Winter.Rows(i).Cells(48).Value IsNot DBNull.Value Then
                summe = CDec(summe + CDbl(DGV_Winter.Rows(i).Cells(48).Value))
            End If
        Next
        tb1.Text = CStr(summe)
    End Sub