BEIJING - A total of 123 million Chinese were aged over 65 by the end of 2011, about 9.1 percent of the total population, the Health Aging Symposium announced Saturday.

Chinese seniors aged 80 or above are expected to take 30 percent of the population aged 65 or above in 2050, and the ratio of working-aged Chinese to the country's seniors will drop from 10:1 in 2000 to 2.8:1 in 2050, the symposium said.

According to the statistics provided by the World Health Organization (WHO), the number of people in the world aged over 60 has doubled since 1980, and by 2050, the number of people aged 80 or above will have reached 395 million, four times the current figure.

The United Nations Population Fund (UNFPA) estimated that in the next five years, the number of adults in the world aged 65 will outnumber children under the age of 5 for the first time, especially in developing countries.

France took 100 years to double its population aged above 65 from 7 percent to 14 percent, while countries such as China and Brazil only took 25 years to achieve the same growth, the UNFPA said.

World Health Day falls on April 7 every year, the anniversary of the founding of the World Health Organization (WHO). The topic of this year is Aging and health with the theme "Good health adds life to years."