Pyramid/Hierarchial graph/chat in Excel

I work in a professional services firm and want to put together a graphical representation of our staff structures by business unit. Typically these will be a pyramid (a few senior staff, reasonable number of middle ranking staff, loads of junior staff) albeit different services lines would be barrel or funnel shaped in their staff mix. What I want to know is if / how can I put this in a graph in Excel. The key is showing the size of a particular grade horizontally (and centred), while showing vertically the same graphical size or space for each grade. Any ideas how I can do this?
Chris Jones