After plarium started making all the new stuff pay or lose and took away the consistancy of bg payouts we had a bunch of players quiting and some left their logins to others, But as of recently we have had a bunch of new players that have come in and pushed the oldies out, It sounds weird at this stage of game implosion for SF but i only know 1 for sure with maybe 4-5 guestimates, may be others but i dont know them.
Of course we took in quite a bunch from sister leagues, maybe thats why it seems so busy there now.
But before our influx of new family i would say 10-30% possible alts with about 12 ish% i knew, not thought.
Maybe im naive, i say we got maybe 5-8% guestimate, (and at least 1 is crusher) but we are slowly narrowing him. LOL
Looking at coordinated attacks from random leagues on certain leagues/players, and putting messages from supposedly different players from different leagues side by side, and keeping notes on certain repeated behavior, I would say that alts are 50-55% accross the server.