The number of Americans who said they had more than five sex partners in the past year, failed to use a condom, had sex in exchange for drugs or money, used illicit drugs, had male-to-male sex or had an HIV positive partner all dropped slightly from 2006-2010 compared to 2002.
About 10 percent of men and eight percent of women in the current survey period reported at least one of these HIV-risk behaviors, down from 13 percent of men and 11 percent of women in 2002.
That means about 6.5 million men and 4.9 million women reported HIV-risk related behaviors in the year prior to taking the latest survey.
The report, issued by the National Center for Health Statistics, drew from a survey of 22,682 people aged 15-44, most of whom answered questions by entering responses into a computer rather than to a live interviewer.
This method "has been found to yield more complete reporting of sensitive behaviors," said the report.
Nationwide, new cases of HIV have leveled off at about 50,000 in the United States each year, with 16,000 people dying annually of AIDS, the Centers for Disease Control said.
About 1.2 million people in the United States are living with HIV, and about 20 percent do not know they are HIV positive.
Thursday's report said that 61 percent of new AIDS infections in 2009 were among men who have sex with men, while 27 percent were attributed to heterosexual contact and nine percent to injection of illicit drugs.
Men who had prison experience in the past year were most likely to report at least one risky behavior -- 27 percent -- compared to seven percent of men who had not done time behind bars.
Men with military experience were also less likely (6.8 percent) than men without (10 percent) to report risky behavior.