This is tearing you apart: how many sex partners has your partner had? A new nationwide survey, employing high-tech methods to require candid answers on sexual activity and illegal drug use, discovered that 29 % of American men report having 15 or more female sexual partners in a lifetime, while only 9 % of women report a similar number of partners.

The average number of a lifetime female sexual partner for men was seven, while women had on average four male partners during their lifetime.

The analysis was made on data collected from 1999 to 2002 for the National Center for Health Statistics, on a pool of 6,237 adults, aged 20 to 59 and did not include the homeless, imprisoned inmates or other institutionalized adults. Unlike in previous approaches, when subjects passed face-to-face interviews, a fact that caused underreporting of behaviors which can be perceived negatively, the new study collected data through computer-assisted self-interviews, which provide complete privacy and favor more honest answers.

"This is the first time we've used this technique. The participants have a headset on, they hear questions, they touch the screen with responses. There's no one else in the room and they can take as long as they want. The findings would provide grist for further studies, notably on the prevalence and patterns of sexually transmitted diseases." said Dr. Kathryn Porter, medical officer for the survey.

The data revealed that 96 % of the US adults have had sex and only about 11 % of never-married adults had remained chaste; 16 % of adults first had sex before age 15, while 15 % abstained from sex until at least age 21. Amongst those having sex before 15, the highest percentage belonged to non-Hispanic blacks (28 %) compared to 14 % for Mexican-Americans and non-Hispanic whites. 6 % of black people had sex for the first time at age 21 or older, less than Mexican-Americans (17 %) or non-Hispanic whites (15 %).

A higher percentage of black men and women reported 15 or more partners in a lifetime (46 % and 13 %, respectively) than other racial groups. 17 % of men and 10 % of women had two or more sexual partners in the past year, while 25 % of women and 17 % of men reported just one partner of the other sex in their lifetime.

26 % of men and 17 % of women have tried cocaine or other street drugs (this does not include marijuana) during their lifetime; 7 % of men and 4 % of women had done it in the last 12 months. Non-Hispanic whites were the most inclined to use drugs (23.5 %), followed by blacks (18 %) or Mexican-Americans (16 %). Married or highly educated people were less likely to test street drugs.