At the time of Attack of the Clones, there are about 10,000 Jedi in the galaxy. We also know of a few living Sith/Dark Side users and Force-sensitives. Is this number representative of the Force users in the galaxy? What is the exact ratio, if it exists?
Given the massive size of the Old Republic and Galactic Empire and that members of seemingly every species can have the ability to use the Force but at the same time people don't believe it's a real thing, the number of people who actually are trained in its use must be negligible. The number of people who have the ability but don't know how to use it, like Luke and Leia, could be much higher, but the total number of Jedi, Sith, and others who can use Force Powers is apparently tiny compared to the galactic population.