Private Function ScaleDatePercents(ByVal perc1 As Double, ByVal perc2 As _
      Double) As Double()
        Dim lst As New List(Of Double)
        Dim totalDays As Integer = (GetDateAtPercent(perc2) - GetDateAtPercent( _
          perc1)).TotalDays
        Const month As Double = 30.4375 ' 365,25 / 12
 
        If totalDays <= 1 * month Then
            '...
        ElseIf totalDays > 1 * month AndAlso totalDays <= 2 * month Then
            '...
        ElseIf totalDays > 2 * month AndAlso totalDays <= 6 * month Then
            '...
        ElseIf totalDays > 6 * month AndAlso totalDays <= 10 * month Then
            '...
        ElseIf totalDays > 10 * month AndAlso totalDays <= 14 * month Then
            Dim startIndex As Integer = CInt((table.Rows.Count - 1) * perc1)
            Dim endIndex As Integer = CInt((table.Rows.Count - 1) * perc2)
            Dim i As Integer = startIndex
            Do
                i += 1
            Loop Until CDate(table.Rows(i)("Date")).Day < CDate(table.Rows(i - _
              1)("Date")).Day
 
            Dim p As Double = (i - startIndex) / (endIndex - startIndex) 'der 
            ' erste Handelstag im ersten "angefangenen" Monat als Prozentwert 
            ' des Bereichs
            lst.Add(p)
 
            '...
        Else
            '...
        End If
 
        '...
 
        Return lst.ToArray
    End Function

    Private Function GetDateAtPercent(ByVal percent As Double) As Date
        Return CDate(table.Rows(CInt((table.Rows.Count - 1) * percent))("Date"))
    End Function

Imports System.Net
Imports System.Data
 
    Public Function DownloadData() As DataTable
        If Not IO.File.Exists(My.Computer.FileSystem.SpecialDirectories.Temp & _
          "\Schema.ini") Then
            Dim s As String = "[table.csv]" & vbCrLf & "ColNameHeader=TRUE" & _
            vbCrLf & "DecimalSymbol=." & vbCrLf & "Format=Delimited(,)"
            IO.File.WriteAllText(My.Computer.FileSystem.SpecialDirectories.Temp _
            & "\Schema.ini", s)
        End If
        Dim wc As New WebClient
        Dim url As String = _
          "http://ichart.yahoo.com/table.csv?s=BAS.DE&a=00&b=3&c=2000&d=03&e=1" & _
          "&f=2009&g=d&ignore=.csv"
        wc.DownloadFile(New Uri(url), _
        My.Computer.FileSystem.SpecialDirectories.Temp & "\table.csv")
        Dim connectionStr As String = "Provider=Microsoft.Jet.OLEDB.4.0;Data" & _
        "Source=" & My.Computer.FileSystem.SpecialDirectories.Temp & ";Extended" & _
        "Properties=""text;HDR=YES;FMT=Delimited"""
        Dim dataSet = New DataSet
        Dim connection As New OleDb.OleDbConnection(connectionStr)
        Dim dataAdapter As New OleDb.OleDbDataAdapter("select * from" & _
          "[table.csv]", connection)
        dataAdapter.Fill(dataSet)
        connection.Close()
        Return dataSet.Tables(0)
    End Function