The second season of HBO's fantasy drama Game of Thrones broke ratings records. It was also the most pirated TV show of the season. The series averaged nearly 4 million illegal downloads per episode, slaughtering the second and third ranked series How I Met Your Mother and The Big Bang Theory, which each averaged about 2.8 million illegal downloads per episode. Here, three lessons to be learned from TV fans' pirating habits:

1. It's time for HBO to cut the cord
The 3.9 million illegal downloads of each Game of Thrones episode is troubling because the HBO epic is the only series to have "as large an illegal audience as it does a legitimate audience," says Patrick Kevin Day at the Los Angeles Times. Ratings for its season finale just barely eclipsed the number of illegal downloads, with 4.2 million paying viewers. Why? Because viewers without cable subscriptions can't watch the show any other way, says Keith Wagstaff at TIME. It's not available for download on iTunes, nor for streaming on Hulu, Netflix, or any other legit site. The high level of piracy supports the movement for HBO to open up its HBO Go service — which only allows HBO subscribers to stream the network's shows — to those who don't subscribe to HBO, but would still pay for individual episodes, says Andre Yoskowitz at Afterdawn

2. CBS needs better streaming options
"CBS has a famous aversion to making [its] content readily available online," says Darren Franich at Entertainment Weekly. That explains why How I Met Your Mother and The Big Bang Theory rank so high on this list. Since the audience demographics of both sitcoms "skews younger/nerdier than the network's other sitcoms, it makes sense that [CBS] would feel the piracy crunch." The network could drive people away from piracy by simply upping its streaming game.

3. Piraters have tastes similar to broadcast viewers
Aside from the prestige cable dramas Game of Thrones and Mad Men, which ranks No. 5 on the list of illegal downloads, the rest of the Top 10 is populated by mainstream network shows, according to Torrent Freak. Shows like How I Met Your Mother, The Big Bang Theory, House, and Modern Family are mass-appealing, highly rated programs — not the quirkier, nerdier fare you'd expect web-savvy piraters to flock to. House, for one, is by some metrics the most popular show in the world, says Franich, so perhaps we shouldn't be surprised that it is also one of the most pirated.