The complaints were the biggest annual increase since the early 1990s.
The data, which was released by the Equal Employment Opportunity Commission, shows allegations of bias based on race, retaliation and sex were most frequent. Complaints about discrimination based on pregnancy rose 14 percent to 5,587 charges last year.
The commission said complaints increased from 75,768 charges filed in 2006 to 82,792 in the last fiscal year, the highest complaint level since 2002, and the biggest annual percentage increase since 1993.
Complaints fell until 2006, when they increased slightly before spiking last year.
According to the allegations, 37 percent of the complaints were based on race; 32 percent were based on retaliation; and 30 percent were based on sex discrimination.