From the Nuclear Regulatory Commission:
The Nuclear Regulatory Commission’s compilation of 2007 nuclear power plant worker doses at U.S. reactors shows the average annual collective dose per plant is 97 person-rem, the lowest ever, and is two-thirds of the dose recorded 10 years ago.
To determine a plant's collective dose, hundreds of workers’ individual doses are added up and the result is expressed in person-rem. The average American receives a dose of about 360 millirem every year from all radiation sources; the average nuclear plant worker in recent years received about an additional 160 millirem each year on the job. NRC regulations allow workers at nuclear power plants to safely receive a job-related dose of up to 5,000 millirem each year.
Here is a chart of the data since 1973.