Aioe.org tries to reject spam messages sent to newsgroups using cleanfeed, an old antispam software written in perl. It plots a nice html statistical page that is printed below. Everybody should consider that these data do not represent a reliable sample of the number of spam messages actually posted on usenet because they only refer to this server.
Filter started: Mon Oct 3 17:51:15 2022
Report generated: Wed Oct 5 20:58:11 2022
Uptime: 184016 seconds
Accepted: 30554
Rejected: 2542
Refused: 0
Period since last report: 3602 seconds
Articles examined (this period): 0.2/s
Articles accepted (this period): 0.1/s
Articles examined (entire uptime): 0.1/s
Articles accepted (entire uptime): 0.1/s
MD5 entries: 254 Rejecting: 24
PHL entries: 447 Rejecting: 6
PHN entries: 369 Rejecting: 1
PHR entries: 0 Rejecting: 0
FSL entries: 456 Rejecting: 0
MID history: 358
Supersedes entries: 0