Source: U.S. Census Bureau, G14-QSPP2, September 2014
From the summary:
For the 100 largest public-employee pension systems in the country, cash and security holdings totaled $3,365.4 billion in the second quarter of 2014. Cash and security holdings had a quarter-to-quarter increase of 4.6 percent, from $3,218.2 billion last quarter, and a year-to-year increase of 14.3 percent, from $2,945.6 billion in the second quarter of 2013. Earnings on investments totaled $129.4 billion in the second quarter of 2014.