I can't speak for every woman so I can't give you a percentage, lol, but personally I'm on the pill. It's not for everyone, but for me I didn't lose/gain any weight, and it hasn't affected my moods, so I like it. The IUD and the pill are probably the most popular. For those few who only use condoms, there's also the morning after pill if a condom were to slip off or break (not an abortion pill, despite what the Republicans try to tell you lol).