I do not think the online registries (pinball owners, pinside, etc.) are a good indication of the games that still exist.
Out of the 9 games currently in my collection, 6 were not registered anywhere and came from owners who wouldn't even know what that is. Go to any pinball show and you’re likely to see a game that you’ve been looking for online but magically someone local brings it. There are some big time contributors on this forum that do not list any of their games on their collection page. I myself had games for the last 10 years and only started participating in online forums in the last couple years.
If I had to take a guess I would say less than 20% of any title survive. I think the attrition rate is very low at this point unless it’s a game that’s parted out by a collector.
