China's population is the world's largest, with 1.3 billion people. To reduce growth, the government sponsors family-planning programs and offers incentives to families with only one child; penalties are imposed on those with more children. This policy applies mainly to the Han Chinese (92 percent of the population). Rural families may have a second child if the first is a girl. Still, the annual growth rate has fallen to 0.6 percent. Of China's 55 minority groups, 15 include more than one million people. These are the Zhuang, Mongolian, Hui, Tibetan, Uygur, Miao, Yi, Buyi, Korean, Manchu, Dong, Yao, Bai, Tujia, and Hani nationalities. While about 60 percent of all Chinese live in rural areas, urban populations are growing rapidly. About 100 million rural migrant laborers move in and out of cities in search of work. Shanghai (18 million) and Beijing (16 million) are the largest cities.