The overall number of 16-year-old drivers in fatal crashes decreased from 1,084 in 1993 to 938 in 2003, while during the same period there was an 18 percent increase in the 16-year-old population.

The number is based on national government statistics analyzed by IIHS, Susan Ferguson, the Institute's senior vice president for research, told National Underwriter.

"This isn't a study of graduated licensing per se," said Ms. Ferguson in a statement. "It's a look at the status of 16-year-olds in states both with and without graduated licensing. Still, this study does reveal some very positive effects of the new licensing systems. The main reason for the decline in the crash rate is that fewer beginning drivers are getting their licenses when they turn 16."

While the number of deaths declined, the ratio of deaths has not. Seventy-three 16-year-old drivers per 100,000 license holders were in fatal crashes in 1993, compared to 74 per 100,000 in 2003.

"In time we do expect to see a drop in the fatal crash rates per licensed 16-year-old driver," said Ms. Ferguson. "This will happen if more states implement stronger restrictions on night driving and on passengers in cars with beginning drivers.

"A number of states don't have these policies, and states that do often allow one or more passengers or apply the restrictions during short time periods. These restrictions are expected to have the strongest influence on fatal crashes per licensed driver."

In the meantime, she said, "studies in several states that have looked at all police-reported crashes, not just fatal ones, have found significant declines per licensed driver."

Teenagers have the highest crash risk of any age group, about four times higher than for older drivers. Teenagers are more likely than older drivers to be in crashes involving driver error and speeding, the Institute said.

"The riskiest time for teens is when they first start driving," Ms. Ferguson pointed out. "The key to the effectiveness of graduated licensing is that it phases in a driver's license over time, keeping teens in the learner phase longer and delaying a full-privilege license until beginners are older, more mature, and more experienced."

Another finding the Institute feels is important is that restrictions on 16-year-olds did not simply shift the crash risk to older teens. Crash rates dropped 11 percent for 17-year-olds and 6 percent for 18- and 19-year-olds.

The figures do not indicate the type of a driving program the older teen drivers went through, Ms. Ferguson told NU, but it does indicate that older teens are safer drivers, presumably because of their maturity.

One of the most dangerous scenarios is when a teenage driver transports other teens and, on a per capita basis, this kind of crash declined 39 percent during the period 1993 to 2003. Meanwhile, most other characteristics of 16-year-olds' crashes stayed the same over time.

A full graduated licensing law has three stages. Beginners must remain in each of the first two stages for minimum time periods: supervised learner's period; intermediate license (after the driver's test is passed) limiting unsupervised driving in high-risk situations; and then a license with full privileges available after completing the first two stages.

Key elements of the intermediate stage include limits on unsupervised driving at night and transporting teenage passengers. Certification by parents that a learner has driven a minimum number of supervised hours also is important.

"Parents are key to the success of graduated licensing," Ms. Ferguson added. "The laws empower parents to set down their own rules of the road and enforce them. This is especially needed because the laws in many states still aren't strong. They don't all have three stages of a true graduated system, and some laws that do have the stages still don't restrict driving at night or with other teens."