Private Function GetFreq1(ByVal week As Integer, _
       year As Integer) As DataTable
 
        'Dim year As Integer = cbx_Jahr.SelectedValue
 
 
        Dim dt As DataTable = ABLAGEPUAM.Vorgang
        Dim cal As Globalization.Calendar = _
          Globalization.CultureInfo.CurrentCulture.Calendar
 
        Dim q = From row As DataRow In dt
              Let wk As Integer = _
                cal.GetWeekOfYear(row.Field(Of Date)("angelegtam"), _
                Globalization.CalendarWeekRule.FirstFourDayWeek, _
                DayOfWeek.Monday)
              Where year = row.Field(Of Date)("angelegtam").Year _
               AndAlso wk = week _
                AndAlso row.Field(Of Integer)("IDAblage") = row.Field(Of _
                Integer)("IDAblage")
              Group By art = row.Field(Of String)("Ablagename") Into Count()
 
        Dim df As New DataTable
        df.Columns.Add("Ablagename") : df.Columns.Add("Count", GetType( _
          Integer)) : df.Columns.Add("Cum", GetType(Double)) _
                                        : df.Columns.Add("CumPerc", GetType( _
                                        Double))
 
        For Each el In q
            df.Rows.Add(el.art, el.Count)
        Next el
 
        Dim bs As New BindingSource With {.DataSource = df}
        bs.Sort = "Count DESC"
 
        Dim sm As Integer = 0
        For i As Integer = 0 To bs.Count - 1
            Dim row As DataRow = DirectCast(bs(i), DataRowView).Row
            'Häufigkeiten kumulieren
            sm += CInt(row("Count"))
            row("cum") = sm
        Next i
 
        'Kumulierte Werte in Prozentanteile umrechnen
        For i As Integer = 0 To bs.Count - 1
            Dim row As DataRow = DirectCast(bs(i), DataRowView).Row
            row("CumPerc") = Math.Round(CInt(row("Cum")) / sm * 100, 2)
        Next i
 
        'Daten in der DGV anzeigen
        DGV1.DataSource = bs
 
        With DGV1
            .Columns(0).AutoSizeMode = DataGridViewAutoSizeColumnsMode.Fill
            .Columns(1).Width = 60
        End With
 
        With DGV1
            .EnableHeadersVisualStyles = False
            .ColumnHeadersDefaultCellStyle.Alignment = _
              DataGridViewContentAlignment.MiddleCenter
            .ColumnHeadersDefaultCellStyle.BackColor = Color.DimGray
            .ColumnHeadersDefaultCellStyle.ForeColor = Color.FloralWhite
            .BackgroundColor = Color.LightGray
            .Font = New Font("Consolas;", 9.5, FontStyle.Regular)
            .ColumnHeadersBorderStyle = DataGridViewHeaderBorderStyle.Single
            .ColumnHeadersHeight = 38
            .ColumnHeadersHeightSizeMode = _
              DataGridViewColumnHeadersHeightSizeMode.DisableResizing
            .RowHeadersVisible = False
            .GridColor = System.Drawing.Color.DarkGray
            .SelectionMode = DataGridViewSelectionMode.FullRowSelect
            .DefaultCellStyle.WrapMode = DataGridViewTriState.True
            .AutoSizeRowsMode = DataGridViewAutoSizeRowsMode.AllCells
        End With
        With DGV1.DefaultCellStyle
            .SelectionForeColor = Color.OldLace
            .SelectionBackColor = Color.Olive
            .BackColor = Color.LightGray
            .ForeColor = Color.Black
            .Font = New Font("Consolas;", 8.0, FontStyle.Regular)
        End With
        With DGV1.AlternatingRowsDefaultCellStyle
            .SelectionForeColor = Color.OldLace
            .SelectionBackColor = Color.Olive
            .BackColor = Color.WhiteSmoke
            .ForeColor = Color.Black
            .Font = New Font("Consolas;", 8.0, FontStyle.Regular)
        End With
        'Ende Auswertung
        'Chart anzeigen
 
    End Function

  Private Sub Monatsliste()
        Dim lst_Monate As New List(Of String) From {"", "Januar", "Februar", _
          "März", "April", "Mai", "Juni", "Juli", "August", "September", _
          "Oktober", "November", "Dezember"}
        cbx_Monat.Items.AddRange(lst_Monate.ToArray)
        cbx_Monat.SelectedIndex = 0
        lst_Monate.Clear()
    End Sub

 Dim dt As DataTable = ABLAGEPUAM.Vorgang
        Dim cal As Globalization.Calendar = _
          Globalization.CultureInfo.CurrentCulture.Calendar
 
        Dim q = From row As DataRow In dt
              Let mn As Integer = row.Field(Of Date)("angelegtam").Month
              Where year = row.Field(Of Date)("angelegtam").Year _
               AndAlso mn = Month(row.Field(Of Date)("angelegtam")) _
              Group By art = row.Field(Of String)("Ablagename") Into Count()
 
        Dim df As New DataTable
        df.Columns.Add("Ablagename") : df.Columns.Add("Count", GetType( _
          Integer)) : df.Columns.Add("Cum", GetType(Double)) _
                                        : df.Columns.Add("CumPerc", GetType( _
                                        Double))
 
        For Each el In q
            df.Rows.Add(el.art, el.Count)
        Next el
 
        Dim bs As New BindingSource With {.DataSource = df}
        bs.Sort = "Count DESC"
 
        Dim sm As Integer = 0
        For i As Integer = 0 To bs.Count - 1
            Dim row As DataRow = DirectCast(bs(i), DataRowView).Row
            'Häufigkeiten kumulieren
            sm += CInt(row("Count"))
            row("cum") = sm
        Next i
 
        'Kumulierte Werte in Prozentanteile umrechnen
        For i As Integer = 0 To bs.Count - 1
            Dim row As DataRow = DirectCast(bs(i), DataRowView).Row
            row("CumPerc") = Math.Round(CInt(row("Cum")) / sm * 100, 2)
        Next i
 
        'Daten in der DGV anzeigen
        DGV1.DataSource = bs

  Dim mnth As Integer
        Dim dt As DataTable = ABLAGEPUAM.Vorgang
        Dim cal As Globalization.Calendar = _
          Globalization.CultureInfo.CurrentCulture.Calendar
 
        Dim q = From row As DataRow In dt
              Where year = row.Field(Of Date)("angelegtam").Year _
               AndAlso mnth = Month(row.Field(Of Date)("angelegtam")) _
              Group By art = row.Field(Of String)("Ablagename") Into Count()
 
        Dim df As New DataTable
        df.Columns.Add("Ablagename") : df.Columns.Add("Count", GetType( _
          Integer)) : df.Columns.Add("Cum", GetType(Double)) _
                                        : df.Columns.Add("CumPerc", GetType( _
                                        Double))
 
        For Each el In q
            df.Rows.Add(el.art, el.Count)
        Next el
 
        Dim bs As New BindingSource With {.DataSource = df}
        bs.Sort = "Count DESC"
 
        Dim sm As Integer = 0
        For i As Integer = 0 To bs.Count - 1
            Dim row As DataRow = DirectCast(bs(i), DataRowView).Row
            'Häufigkeiten kumulieren
            sm += CInt(row("Count"))
            row("cum") = sm
        Next i

'Auf dem Formular eine Listbox für Monatsauswahl erstellen
Dim WithEvents Months As New ListBox With {.Parent = Me}
 
'Im Load-Event der Form diese Listbox füllen
'(Geht auch direkt per Rückgriff auf die entsprechende Enumeration)
For i As Integer = 1 To 12
   months.Items.Add(DateAndTime.MonthName(i))
Next i
 
'Im Listbox-Event die Graphik anfordern
Private Sub Months_SelectedIndexChanged(sender As Object, _
    e As EventArgs) Handles Months.SelectedIndexChanged
 
    Dim lbo As ListBox = DirectCast(sender, ListBox)
    if lbo.selectedindex >= 0 then _ 
       Getfrequencies(2017, lbo.SelectedIndex + 1)
End Sub
 
 
'So muß die gerufene Methode deklariert sein
Private Sub getfrequencies(ByVal year As Integer, mnth As Integer)
   'Linq-Code etc.       
End Sub