About a quarter of Beijing's registered residents were over 60 years old at the end of 2017, according to a white paper published by the capital's office for senior citizens on Monday.

The number of elderly in Beijing rose from about 2.63 million in 2012 to 3.33 million at the end of 2017, accounting for 24.5 percent of the capital's registered population.

Beijing sees an average increase of over 500 people at or above the age of 60 each day and a daily rise of about 120 people at or above the age of 80.

The number of registered residents who are aged 60 or above in Beijing is expected to reach 3.8 million by 2020, according to the office.

The white paper also showed that elderly people in the capital tend to live a longer life. Old people at or above the age of 80 accounted for 3.3 percent of the total population in Beijing in 2012, and the figure rose to 4.1 percent in 2017. The number of centenarians in Beijing also rose from 544 in 2012 to 833 in 2017.

China's population is aging rapidly. The number of people aged 60 or above reached 241 million in China by the end of 2017, accounting for 17.3 percent of the total population. The number is expected to peak at 487 million around 2050, accounting for a third of the total population, according to the Office of the National Working Commission on Aging.