The annual investment yield for the national social security fund averaged 8.4 percent in the 16 years since it was established, according to an official from the National Council for Social Security Fund (NCSSF).

Wang Zhongmin, vice chairman of the NCSSF, disclosed the information at a seminar on Monday.

Established in 2000, the national social security fund was designed to aid the country's aging population and be a strategic reserve to support future social security expenditure.

The funding sources include fiscal allocation from the central government, allocation from the lottery public welfare proceeds, individual contributions and capital raised by other methods approved by the State Council.

By the end of 2015, the fund's managed assets totaled 1.9 trillion yuan (276.6 billion U.S. dollars), according to a report from the NCSSF.

About 54 percent of its assets were invested via entrusted bodies, while 6 percent were invested overseas, according to the report.