Statistical information on internal audit staffing

Does anyone know of a good source or reference where I can find information on the recommended staffing of internal auditors for a $1 billion bank? I've been searching the web and FRB and haven't come up with anything useful. Please help!

I don't know of any recommendations for asset size/audit staff. I think it's more workload, risks, etc., and it would be a Management decision.

Feeling understaffed?

Try www.theiia.org

Well, we are not feeling the crunch yet, but just to have docs to justify the hiring of an extra person for the future.

We're a 1.1B bank and have no internal auditors. Everything is outsourced.