In my open matte master list, there are about 3000 titles; even discarding the double ones due to different formats, and the ones still not checked and that would be indeed cropped and not open matte, there would be more than 2500 open matte/fullscreen titles… that are a bit more than 1% of all released movies - should also add that the list is mainly focused on US movies.

Personally, I do not consider the open matte version the “real deal”; yet, if available, I’ll grab it as an alternative version - and usually mics and other props aren’t visible in open matte versions (1.78:1) while could be more probable on fullscreen (1.33:1) ones.