Crysis 2 in the top spot? That game was horrible. Not even as good graphically or gameplay-wise as the first Crysis. People probably pirated it because it was crap and they didn't want to waste money on it.
The next three games: MW3, BF3, and FIFA... Why would you pirate these games? They're only good for their multiplayer. Also, I'd like to confirm now that I am a MW hater. I played that game 10 years ago when it was called Counter-Strike.
Last on the list is Portal 2. Booo to you pirates! Don't mess with Valve, they're like the last decent PC developer. I say BOOOO to you pirates.