Schneider manufactured 90mm Angulons for nearly 40 years and it was very popular lens. Tens of thousands would an estimate at the low end and likely a lot more. The Angulons have been hard to sell for the last few years because of of the glut of more modern 90's with better optics and more coverage. I'm guessing a lot of people have these sitting in drawers.
the trouble with this train of thought is do the people with them sitting in a drawer know/remember/care. Will they get around to selling them?