Back in April this year, the University of Ballarat conducted a study of Bittorrent usage. They've concluded that 89.9 percent of Bittorrent usage is infringing copyright. So it's no surprise that AFACT have jumped on this report as if it were the Holy Grail.
The study tracked over a million individual files shared over Bittorrent by monitoring 17 of the most popular trackers on Torrentz.com, but ultimately found that the most shared files equated to just over 15,000 torrents.
To work out that 89% illegal figure, the study took a selection of 1000 random torrents and calculated their legality. If in doubt, they erred on the side of caution. 1000 out of over a million torrents isn't exactly the kind of percentage I'd accept to make this statistic indisputable, but it's certainly a good enough sample for AFACT to claim as proof of the evils of the Bittorrent protocol.
What the study didn't delve into was whether or not any of the people who torrented actually went on to purchase a copy of their downloaded file legitimately. It also didn't track how many of the torrents were downloaded by celebrities.
In any case, expect to see this report flung around by AFACT every chance they get...