But the most people speak Mandirin... However more people don't speak it. I think the UN believed what ever language the Indian's speak (as in India, not Native Americans) would grow even bigger within the next 50 years, they have a higher population growth than China.
Whatever language you are born hearing is your easiest language. If you were raised in a bilingual family, you probably know both. I bet people in Spain wish everyone spoke Spanish.
But I don't like foriegn languages much, I don't like studying them.