Unfortunately, I can't tell you how many horse beads exist in the world!
* There are too many: Horse beads have been made for centuries in various materials and styles. There's no central registry or count.
* They are constantly made: New horse beads are created all the time, and some may be lost or destroyed.
If you're interested in a specific type of horse bead, perhaps you can narrow down your search to a specific brand, material, or era. Then, you might have more luck finding information about the quantity produced.