On Usenet, someone mentioned about 8500 PS2 titles released worldwide, which would mean we're talking about a 12% range. Apparently, about 2500 PS2 were released in Europe (no idea if that's true...), so we're still under 50%. What probably bothers most people is that they're getting something like less than 50%-12% compatibility (depending on your point of view) for more money than the rest of the world...