In Finland in 2019, 625000 used cars were sold vs. 114200 new car registrations. I believe these include both private and company cars, though.
This would be 85% used cars, 15% new cars.
The average age of a bought used car was 13.3 years.
https://www.kauppalehti.fi/uutiset/uutta-dataa-kaytetyn-auto...