I don't know of there is a simple answer to those questions, since the rifles have come into the country in several batches over a long period of time. Around 2005, I went to Wolverine arms to buy a PTRD (I think they got 16 of them in then, but can't say for sure) and John pointed out that they also got in 4 PTRS. I went home with one of each. Whomever imported them brought in more, as they also turned up at Marstar and at collectors source.
There was a database online from the Ottawa Citizen at one time which listed all guns registered by model and other data liek th eowners postal code. It might have come close to giving you the answer, but only based on what was imported while the registry was in effect, as well as pre-registry examples whose owners actually registered them. Not all owners did.