China's Population & The One Child Policy

As of January 2011, the worlds population was about 6.7 billion people.  China, with a population of 1.3 million people represents about 20% of the worlds overall population.  This makes China the worlds most populated country.  This though may not stay this way because of China's one child policy which began in 1979.  It was originally designated as a temporary measure because of it's over-population. The policy still continues today.  This policy limits couples to only having one child.  Over the first 20 years it reduced China's population by 300 million people.

http://www.historycentral.com/nationbynation/China/Population.html

This chart shows China's population growth from 1980 (right after the one child policy was put into place) to 1996.

http://geography.about.com/od/populationgeography/a/onechild.htm
http://geography.about.com/od/populationgeography/a/chinapopulation.htm