Yes, it greatly depends on when you took the census. At one point the elves, I think would have outnumbered everyone. Hobbits were mostly concentrated in a pretty small area so they wouldn't have been too high in number.
Its not like they had a ME post office! It'd take years to go to all the various corners if you were able to survive.
Personally, at the hight of Gondor's glory, I would think that there'd have been aprox. 29,000 give or take a few men. But I don't really know, its just a guess.
