And? How does that differentiate between people who wouldn't have bought the game anyway and people who would but didn't? The only thing that tells you is that there are people using your game and the system doesn't account for them. It doesn't tell you anything else.
There's only one way you can ever get an accurate account of that figure.
1) Release the game in some alternate dimension where there's no piracy and everyone is good and pure and rich beyond all measure.
2) After a few decades, when the patent expires, jot down the total number of users over this period and time travel back to the past into this dimension.
3) Release the game with no DRM, no copyright software, nothing in this dimension.
4) Wait a few decades again, then jot down the total number of users over that period.
Then you compare the total number of towers of goos from those two sessions.
My point is that while piracy is still bad, I wish people would stop taking it out of perspective. It's like those raving lunatics running around screaming about peak oil. Or those kinds of people you can trick by telling them di-hydrogen monoxide is a toxic substance. So yes. Piracy is rampant. Yes, piracy probably affects sales. But how many of those pirates would have bought the game anyway? It's kinda like a blacksmith complaining that fishermen aren't buying from him or birds complaining that earthworms eat all their food.