Maybe insurance companies have more up-to-date info. Even project cars are being insured to some extent. Not that they would share that info readily,but the info is there. After 50 + years of abuse,rust,fires,floods,tornadoes,hurricanes,collisions,thefts,etc many are “gone”/eliminated. From about 1981-1992 our cars were not “treasured”. It did not take much damage to “total” one out. Once they hit the junk yards they were quickly parted out,the hulk got sold by the pound.
Since we are all just giving opinions on this subject,mine is that approx 60% remain in existance. Of that number many will never see the road again. JMO