(Reuters) - Assets of the 100 biggest U.S. public employee pension systems rose a scant 0.09 percent to $3.25 trillion in the first quarter of 2016 from the prior quarter as earnings from investments slowed, U.S. Census data showed on Thursday.

The funds gained $14.4 billion on investments in the first three months of 2016, but that represented a 77 percent drop from the revised $62.3 billion earned in the prior quarter. Earnings fell 81 percent from the revised $75.1 billion in the same quarter last year.

Total contributions from both employers and employees fell 5.1 percent to a combined $39.8 billion from $41.9 billion in the previous quarter.

Corporate stock holdings grew from the previous quarter's total, rising to $1.19 trillion from $1.17 trillion. Holdings of corporate debt rebounded to $417.8 billion, a gain of 2 percent. That contrasts with a 1.9 percent drop in holdings of federal government securities.

(Reporting by Stephanie Kelly; Editing by Tom Brown)