Looking for rough market size numbers & %'s for various email client
software, data within the past 1-2 years, ideally reported from a
reliable 3rd-party (vendor #'s are ok, but not necessarily preferred).

in particular, looking for data on:
- Outlook
- Outlook Express
- Hotmail
- AOL mail
- Yahoo mail
- Eudora
- Netscape
- others > 5% of overall market

(if possible, regardless of whether solution is installed sw or hosted
service, would like to get sense of *active* # of users / licenses, as
opposed to every hotmail or AOLmail account that has been created
since the beginning of time ;)

goal is to determine order & priority of platform development /
relative population size.