Quidditch is the most popular sport just in Europe. In America, they prefer the sport Quodpot.

(At Quodpot, two teams with 11 members each battle. It's about getting the high explosive Quod as fast as possible into the pot. Explodes the Quod before it's placed in the pot, the respective ball carrier is exited from the whole game.)

According to Rowling, there are about 3,000 wizards living in Britain.