The volunteer rates for both men and women -- 22.2 percent and 28.4 percent -- declined for the year ending in September 2013. The bureau said women still volunteered at a higher rate than men across all age groups, educational levels and other major demographics.
Volunteering data were collected through a supplement to the September 2013 Current Population Survey, a monthly survey of about 60,000 households that obtains information on employment and unemployment for the nation's civilian non-institutional population age 16 and over.
The bureau said the volunteer rate in 2013 was the lowest it has been since the supplement was first administered in 2002.
Broken down by age groups, the 35-to-44-year-old group was most likely to volunteer at 30.6 percent. The volunteer rate, was lowest among 20-to-24-year-olds at 18.5 percent. The data indicated the volunteer rate tapered as age increased for persons at least 45 years old.
Volunteers spent a median of 50 hours on volunteer activities during the period from September 2012 to September 2013, the BLS said.