What are all the computer languages that exist, and how many people use them?
Oh, and the VAX BASIC I used in the late 1980's was NOT the same as the BASIC on MS-DOS. Fortran IV and Fortran 77 were also significantly different. Hmmm... but if different versions are that much different, then perhaps it should be limited to current languages. It might be interesting if to know more than 15 people ever used System-J, or if anyone did any serious programming in VAX-DCL, but it's of more value to know more about languages I might actually encounter.
Take a look at this list: http://en.wikipedia.org/wiki/Timeline_of_programming_languages