Around 304 million people had participated in the country's endowment insurance system by the end of 2012, according to an annual statistical report from the Ministry of Human Resources and Social Security on Tuesday.

Among them, nearly 230 million were corporate employees and 74 million were retired workers.

In 2012, China's pension fund collected 2 trillion yuan ($327 million), a year-on-year increase of 18.4 percent. In the same period the expenditure of the fund stood at nearly 1.56 trillion yuan, a 21.9 percent rise from the previous year.

The balance of the fund stood at 2.39 trillion yuan by the end of 2012, according to the report.

The report also revealed that the average annual wage of employees in the non-private sector was 46,769 yuan in 2012, a year-on-year rise of 11.9 percent.

The average annual wage of employees in the private sector was 28,752 yuan, a 17.1 percent rise from 2011.

In 2012, 25 provinces, autonomous regions and municipalities adjusted their minimum wage levels, with an average increase of around 20 percent.