Simply because, China is the most populated country in the world, and the Chinese Gov't came up with a rule, called the "one Child policy". If a Chinese couple chose to have more than one child, they'll be taxed so heavily by the Chinese gov't which will lead the couple to poverty
China and India have implemented population control measures in the past, such as the one-child policy in China. Other countries may have voluntary family planning programs to help manage population growth, but not explicit population control measures.
The population of China was 1.14333 billion in 1990. (Unofficial statistics, for your reference only)
== == The population of China is 1.3 Billion.
The country with the largest population in the world is China.
The population of Bank of China is 2,010.
Bank of China's population is 389,827.
The population of China Steel is 9,071.
China Steel's population is 2,006.
China Sunergy's population is 1,607.
China Minmetals's population is 146,000.
The population of China Nepstar is 14,793.
China Nepstar's population is 2,009.