vb 2008 console application histograms!

I needed to to make a histogram with catogories of different marks by students from 0-100 using "*" to indicate which mark boundary its is represented horizontally i need it to be shown vertically it is in.il show you my code so far :

Module Module1

Sub Main()

Dim Mark As Integer
Dim Cat1 As Integer
Dim Cat2 As Integer
Dim Cat3 As Integer
Dim Cat4 As Integer

Console.WriteLine("Cat1 = 0 to 29 " & "Cat2 = 30 to 39 " & "Cat3 = 40 to 69 " & "Cat4 = 70 to 100 " & "Marks")

While (Mark <= 100)

Console.WriteLine("Enter The Mark")

Mark = Console.ReadLine()

If (Mark >= 0) And (Mark <= 29) Then
Cat1 = Cat1 + 1
Console.WriteLine("That is Cat1: " & Cat1)
ElseIf (Mark >= 30) And (Mark <= 39) Then
Cat2 = Cat2 + 1
Console.WriteLine("That is Cat2: " & Cat2)
End If
If (Mark >= 40) And (Mark <= 69) Then
Cat3 = Cat3 + 1
Console.WriteLine("That is Cat3: " & Cat3)
End If
If (Mark >= 70) And (Mark <= 100) Then
Cat4 = Cat4 + 1
Console.WriteLine("That is Cat4: " & Cat4)
End If


End While
Console.WriteLine()
Console.Write("Marks 0-29")
For Cat1 = 1 To Cat1
Console.Write("*")
Next
Console.WriteLine()
Console.Write("Marks 30-39")
For Cat2 = 1 To Cat2
Console.Write("*")
Next
Console.WriteLine()
Console.Write("Marks 40-69")
For Cat3 = 1 To Cat3
Console.Write("*")
Next
Console.WriteLine()
Console.Write("Marks 70-100")
For Cat4 = 1 To Cat4
Console.Write("*")
Next
Console.ReadLine()


End Sub

how can i show this whole histogram data vertically. If you can help i will appreciate alot thank you :)