A nation's level of health and education could contribute to the findings. It's conceivable that people in developed countries have more information about sexuality. And they're also healthier. Being better informed, and being in better shape, they may be more able to maintain a satisfying sex life.

There's a wide assumption that everybody's engaging in a lot of sex, and it's just not true. Even people who are engaging in sex aren't doing it as frequently as other people think they are.