a few months back (maybe 6?) fotolia mentioned how many contributors they had and I can remember but it was slightly higher than SS
of course if a site just made a figure up for number of images or contributors you cant tell.
a little while ago there was a thread discussing number of active contribs. it was guessed at 70-80% inactive and would never reach pay out look at fotolia rank thread, it gives a rough idea of how active / number of contrib's
about a year old on that thread - quote araminta
On DT, you can easily get similar interesting info by searching for contributors... 18'000 contributors, 60% with less than 10 downloads (!), 20% with more than 100 downloads, 3% with more than 1000 downloads.
Phil