BEIJING, March 24 -- China's social security fund gained 139 billion yuan (22.7 billion U.S. dollars) from investment in 2014, with an 11.4 percent return on investment, the National Council for Social Security Fund said on Tuesday.

The rate of return outperformed the 6.2-percent return rate in 2013.

Founded in 2000, the fund is designed to solve the country's aging problem as well as being a strategic reserve to support future social security expenditure.

By the end of last year, the fund's managed assets totaled over 1.5 trillion yuan.

The fund manager vowed to improve yields this year by strengthening the scientific and lean management on fund investments.

During the 2010-2013 period, losses incurred by bad management totaled 17.5 billion yuan despite the overall success of investments, according to an National Audit Office report.