Registrations are always open on this tracker, invite isn't needed.

http://evopt.org/signup.php

this are the official statistics:

Registered users 58.469
Unconfirmed users 5.319
Male users 12.647 751
Female users 751
Not connectable users 15.339
FreeLeech Off

Torrents 19.889
Dead torrents 684
Total Peers 32,473
Seeders 30,937
Leechers 1,536
Leechers/Seeders 2014%