I think the following sources contain what you're looking for. I ask
you please to look directly at them instead of reproducing the data in
here, to remain in the safe side of copyright issues. Please mind that
the information available out there is mostly estimates which have not
been verified yet.
First, there is the blog Clickable Culture
), which has compiled information from two sources. The problem with
this information is that it dates back to March, and given the fast
growth of Second Life, it can be considered outdated in terms of
absolute numbers. For that reason, please also check the article The
Magic of a Million, at the demographics section of the blog New World
Notes -- specialized in Second Life --
(http://nwn.blogs.com/nwn/demographics/index.html ) Actually, you may
find interesting the whole section.
I believe I've answered your question with this data. Otherwise,
please let me know by posting a request for clarification, and I'll be
happy to help you further.