An estimated 85-90 percent of the population lives in rural areas. Ethnically the population consists of about 90 percent Khmer, 5 percent each of Chinese and Vietnamese and small numbers of hill tribes (Chams and Burmese). Khmer is the country's official language. It is spoken by more than 95 percent of the population. French, as a second language is also spoken, mostly by older people. English is more commonly spoken by the younger generation.
The Cambodian population presents several important features. First, due to the baby' boom after 1979, it is a young population with at least half (50% according to some sources, more according to others) under 18 years of age now. Secondly, the proportion of women in the adult population is high, 56% of those who are 18 years old or more being females. Also as a result of the war, there is a rather high proportion of women-headed household; at least 25% according to UNICEF.
The population of Cambodia is 12,491,501 (2001 estimate). Population growth per year is estimated at 2.3 percent, one of the highest rates in Asia. The rate of infant mortality is also high. The population density is 69 persons per sq km (179 per sq mi), with the densest concentrations on the heavily cultivated central plain. The mountainous regions of the country, where malaria is widespread, are thinly populated, as are the poorly watered northern provinces.
(Source: www.cambodia.gov.kh)