Top-50 Report

Remember, this just looks at the classful routes and tries to cidrize
them at the origin AS level. It assumes no holes either so it's quite
possible to get a lot more back. Yes there are 31K classful routes. That's
either a lot of legacy or not a lot of aggregation.

Given that the routing table stood at 28000 when CIDRD was killed off, I'd
say that there have either been some recent classful allocations, or a lot
of ancient networks suddenly getting advertised.