Teen sex, as well as drug and alcohol use has declined compared to the 1990's, but Hispanics are not sharing in the progress, according to a new federal survey.

Hispanic high school students use drugs and attempt suicide at higher rates than their black and white classmates, the Centers for Disease Control and Prevention survey found.

The CDC questioned 14,041 students in grades nine through 12 in 39 states in the spring of 2007 on a range of risky behaviors.

In 1991, 54 percent of the high school students said they had ever had sexual intercourse, compared to 48 percent in 2007. In 1991, 19 percent said they had at least four sexual partners, compared to 15 percent last year, the survey showed.

For the students overall, just under half have had sex, 75 percent have tried alcohol and 20 percent smoke.

The study is given to high school students every two years. The new report noted that black and white students are reporting less sexual activity than in years past, but there was no decline among Hispanics.

However, whites reported the highest rates of smoking and heavy drinking, while blacks reported the highest rates of obesity and violence.

Hispanic students were more likely than either blacks or whites to attempt suicide, ride with a driver who had been drinking alcohol, or use cocaine, heroin or ecstasy.

Hispanics also most often drank alcohol on school property, were offered or sold illegal drugs, and occasionally skipped school because they feared for their safety, according to the 2007 survey by the Centers for Disease Control and Prevention.

Experts were unable to come up with an explanation for why Hispanic behavior trends differed. However, they speculated that school environments many Hispanics face may differ considerably from what adolescents of other races encounter. Earlier research found that Hispanics and blacks more commonly attend highly segregated schools than whites or Asians.

"There's tremendous segregation in our schools," said Howell Wechsler, director of adolescent and school health for the CDC. He said he was "very troubled" Hispanic teens had not improved in certain risk areas at the same rate as blacks and whites.

The survey did not collect information on the parents' income or education levels. Some experts say those factors also can be a strong indicator of a youth's health behavior and academic achievement.

Adolescents cannot always be counted on to tell the truth about their sexual exploits, drug use, or other risky behaviors. But CDC officials say they take many steps to secure accurate responses: Participation is confidential, kids are spaced apart when answering the questions and teachers do not hover.

The survey asks about a wide variety of behaviors, including sunscreen use, seatbelt avoidance, drug use and suicide attempts. Among other findings, the study noted the proportion of kids who said they recently smoked a cigarette was the same as the proportion who recently used marijuana — 20 percent.

Like the 2005 survey, the 2007 data showed higher rates of risk-taking by Hispanics in several areas.

One example: About 10 to 11 percent of Hispanic students said they attempted suicide, compared with around 7 percent of whites and 8 percent of blacks.

One striking behavior in which blacks fared the worst was television watching.

The American Academy of Pediatrics recommends no more than two hours of daily TV viewing a day for kids. Physical activity is needed to develop mental and social skills and help prevent obesity, and TV violence has been associated with more aggressive behavior in children who watch a lot of it.

Overall, TV watching by high school students has been generally steady, with about 35 percent watching three or more hours a day.

But the new report shows that about 63 percent of black students watch three or more hours a day. In contrast, 43 percent of Hispanic students and 27 percent of whites watched too much TV, the report concluded.

"We don't see that kind of gap" in virtually any other measurement of risky health behaviors, Wechsler said in the interview.

The survey also found that more blacks use computers for non-school activities — like video games — than whites or Hispanics.

The study's findings may indicate that black children have fewer sporting events, social clubs or other after-school options than whites or Hispanics, said Ralph DiClemente, an Emory University researcher who has studied adolescent health and media exposure.

The Associated Press and Reuters contributed to this report.