I would like to know how many distinct Yahoo and MSN groups there are,
and how many active members there are in each of these groups.

More specifically, what I want to know is the approximate number of
total, lasting Yahoo Groups, and  approximate number of total, lasting
MSN groups, as well as the approximate number of active visitors to
each of these groups.

Ideally I would like to find a web site that has detailed, ongoing
information and statistics, similar to what I have found in numerous
places about the Usenet.

I have found web sites that show this sort of information for Usenet
discussion groups, but not for Yahoo groups or  MSN groups.

I know that users can create their own groups, so that in theory there
could be an infinite number of groups, but most of these on-the-fly
groups are short lived and not of interest to anyone.

A general answer such as  "a lot" or "infinite" is not worth anything
to me.

I have spent time looking for this information on the yahoo groups
pages and the MSN groups pages, but can not find the answers there.
Hopefully you will know a great web resource for me and point me
towards it.

Thank in advance for your effort. Please try to do a good job. If you
do I will leave a good tip.