marketshare

i'm trying to figure out which MTAs, both opensource and
commercial, have the most marketshare.

i'd like to see a chart in the form of
postfix N%
sendmail N%
exchange N%

and so on.  ... where the marketshare is defined in two
ways, number of end-user mailboxes, and number of
organizations.

same for MUAs: mutt, squirrelmail, mac mail, eudora, outlook
express

can anyone help?  i need this data to help write an HSARPA
grant proposal.