It's probably a billion dollar business by now.
But then, I'm not completely insane. Laws often are.
http://arstechnica.com/tech-policy/2013/06/pirate-bay-data-s...
Earlier this week, Prenda faced a new and serious allegation: that it had actually put some pornography on BitTorrent itself, intending for it to be downloaded so that it could start a campaign of lawsuits and threat letters.
The Pirate Bay gave the data to TorrentFreak, which says that the IP address 75.72.88.156, which uploaded some porn files that Prenda has litigated over, "was previously used by someone with access to John Steele’s GoDaddy account."
http://arstechnica.com/tech-policy/2015/07/pirate-bay-founde...
http://arstechnica.com/tech-policy/2015/06/judge-finds-prend...
Estimates of 500,000 yearly C&Ds in Germany from 2011.
>http://www.wortfilter.de/news11Q1/news3945.html
C&D industry in Germany makes about 400 million a year.
Don't have numbers from other countries, but it's definitely a big business in Europe.
Swarm information is not enough as it doesn't prove that any data has been transfered.