In response to John Tuttle's question, I think he has answered it best
in his last alternate answer:  "Who knows?"

There would be no way to estimate this as roll-playing pianos have been
and are being gutted or destroyed at an alarming rate, and have been so
since the devices were first made.  To how many attics, barns,
basements, garages and the like have they been relegated, if not
destroyed, dumped, plowed under, made into desks or liquor cabinets,
and the like?

Nice try, but I doubt one can get any true answer.

Best wishes - Lee Munsick