There is at least 100 different films from every year from 1931 to 1999 it looks like (obviously many more from the 80s and 90s). But even just considering that, that's 7K as an absolute minimum. With straight-to-video and TV films the 90s peaked with ~850 unique films from 1995 alone playing on television. And to just give an idea of the level of obscurity, the median IMDb vote count for 1995 is 500, so half are on the level of something like https://www.imdb.com/title/tt0122968/ (which yes, played 7 times, mostly on TMC in March of 1996). Also once you get very obscure things get all muddled. Like with https://www.imdb.com/title/tt0112363/ which is marked as 1995 but certainly appears to have played once on television in 1991 so IMDb is wrong in this case. And of course there are a number of mistakes due to titles matching which I'm slowly correcting.
There are some caveats. This guy: https://www.imdb.com/title/tt0222755/, played 6 times, but on channel 41 (which at the time was Spanish language maybe?), so it has 0 votes on IMDb, but played 6 times on television, which is odd but not unheard of. But you do have to consider that this is using a slightly larger range of channels (some specific to the New York region, like CUNY and MSG) than one might expect. I would guess though that maybe 40% of films play on TCM, SHO, MAX, or HBO ultimately though. Most channels didn't play movies ever outside of primetime.