The proportion of Chinese among the world's population has dropped from 22 percent to 19 percent over the past 30 years, a government official said on Monday.

China's population by the end of 2010, 1.339 billion, accounted for 19 percent of the world's total, compared with 22 percent in early years of the reform and opening-up period that began in 1978, said Li Bin, director with the State Population and Family Planning Commission, at a ceremony to commemorate the World Population Day.

Li said that China will continue its policy to maintain a low birth rate and improve the quality of life for its population, adding that the government has to deal with the unbalanced sex ratio.

China's ratio of infant and maternal mortality was the lowest among developing countries, according to Li. The average life expectancy of Chinese citizens has increased from 68 years old 30 years ago to 73.5, which matches the standard of moderately developed countries.

According to China's latest census, the sex ratio at birth was 118.06, which means there were 118 male births compared to 100 female.