From People’s Daily Online (link):
China has had the largest number of the aged people of 143 million in the world, accounting for one fifth of the world’s total.
It’s predicted that in the 21st century, China will undergo three periods of population aging.
From 2001 to 2020, it will be a phase of rapid aging. China’s elderly population will increase by 5.96 million each year, with an expected aging population of 248 million by 2020.
From 2021 to 2050, China will experience an escalated process of aging. The elderly population will hit 400 million by 2050 and the number of people over 80 years old will be 94.48 million.
From 2051 to 2100, China will enter into the most severe aging phase with the aging population reaching a peak of 437 million. Afterwards, the number will start to decline and stabilize at 300-400 million.