Fifty-one percent of employees in private industry participated in a retirement plan in March 2006.
Twenty-percent of employees participated in defined benefit retirement plans, and 43 percent in defined contribution plans. (Some employees participate in both types.)
These data are from the BLS National Compensation Survey program. Learn more in "Employee Benefits in Private Industry, 2006" (PDF) (TXT), news release USDL 06-1482 and in "National Compensation Survey: Employee Benefits in Private Industry in the United States, March 2006," (PDF) Summary 06-05.
Bureau of Labor Statistics, U.S. Department of Labor, The Economics Daily, Retirement plans in 2006 at https://www.bls.gov/opub/ted/2006/aug/wk3/art05.htm (visited December 09, 2022).