Bell Curve with random values? That ain't gonna happen in this world.

Place the Bars labels in a Frame. Under the Frame, organize the values Labels.

Add this line to the beginning of the StartRandom sub 
Dim MaxHeight as Double
Under the With UserForm1 line, add 
MaxHeight = .Controls("Frame1").Height
Inside the For Each loop, replace .Controls("Bar" & i).Width = 100*R with 
With .Controls("Bar" & i)
   .Height = R * MaxHeight
   .Top = MaxHeight - (1 - R)
End with
Note that I did not redownload the workbook, so I am working from memory.