I personally believe that out of the nearly 10,500 cars produced, that there are probably around two-thirds of them actually still in circulation, which would make around 6,700 in total, worldwide. And out of those, I'd expect that around 5,000 are actual running cars, with the others non-running/sitting, undergoing restoration, and so forth.
So, roughly half of total production is still in active use/on the road. That's a pretty high percentage.
Of course those are my personal guesses. But there are A LOT of cars out there, and new cars come out of the woodwork regularly. I would say that at least with US cars, we have tracked/identified the majority of them over the years (although I do not have the VIN numbers of a lot of our members' cars). But there were only 1,500+ cars brought into the US, so honestly, not that many to track. I have believed for a long time that around 1,000 of the US cars are still in circulation, and this number likely goes down by ~10-12 cars a year due to accidents, neglect/parking, and other causes.
People worldwide hoarded/conserved these cars from the get-go, knowing they were something special, and this is reflected in the relatively high numbers of them that you see still in existence and active use.