I'm not aware of the current state of things in Europe or elsewhere, but for the last couple of decades I have been seeing reports and stories (many confirmed by local control sectors and even by the FAA itself) that there are few actual high-level radars (the ones that bounce a radio wave off the aircraft skin rather than querying its transponder) left in the US ATC network!
The only place where actual radars are left in numbers in civilian service is in the lower altitudes that are relatively near airports with sufficient traffic to justify the expense.
Everything else in the ATCT network relies completely on transponders to both locate and identify aircraft.