There are more older drivers on the road now than young ones, says a new University of Michigan study, prompting researchers to ponder: Who's safer behind the wheel? New drivers or old drivers?

U.S. drivers had better hope its the latter, because a sinking percentage of younger drivers are getting their licenses. Aged drivers represent a growing share of motorists.

In 1983, a third of all drivers in the U.S. were under 30 and 50% of all drivers were under 40 years old. In 2008, just 22% of drivers were younger than 30 and 40% of all drivers were younger than 40.

"Overall, the future evolution of these changes will have potentially major implications for future transportation and its consequences," said Michael Sivak, one of the researchers from the University of Michigan Transportation Research Institute. The shift in demographics will impact the kinds of cars people buy, the safety features automakers provide and even the environment, he said.

Who's safer?

Even though there appears to be a bias against older drivers, novice drivers are the riskier group on the road.

"Younger drivers are worse than older drivers," said Loretta Worters, vice president of the Insurance Information Institute. That's because they are immature and inexperienced. "Teens' lack of experience affects their recognition of and response to hazardous situations, and results in dangerous practices such as speeding and tailgating."

Younger drivers are taking their time getting licensed. In 1983, about 87% of 19-year-olds had earned their drivers' license. In 2008, that dipped to about 75%. The dip has been similar for 16-, 17- and 18-year-olds whose licensed driver percentages dropped anywhere from 15 to 19 percentage points.

Oddly, the Internet may be part of why they are staying off the roads.

"It is possible that the availability of virtual contact through electronic means reduces the need for actual contact among young people," Sivak said. "Furthermore, some young people feel that driving interferes with texting and other electronic communication."

There might be economic reasons for the decline, too. Getting teen children a license means more insurance and buying a car. With the economy in its current state it can be difficult to make this a reality.

The boom in older drivers

Drivers above 40 are on the rise. In 2008 the older-than-70 set made up more than 10% of the overall driving population in the U.S., making it the largest licensed demographic.

In 1983, drivers in their 50s and 60s consisted of over 84% licensed drivers. That figure has spiked to 95%. Most dramatically, the 65- to 69-year-old set jumped to a 94% licensed population in 2008, up from 55% in 1983.

Though they may be safer drivers over all, older drivers have more risks of facing serious injuries due to frailty. NHTSA reports that 5,533 people age 65 and older were killed in car accidents in 2009 -- 16% of all Americans killed on the road. Research suggests they die at greater rates than other age groups because crashes affect their bodies more seriously.

Because of the increase in fatalities and the increase in older drivers on the road, government agencies may scrutinize and regulate older drivers more closely.

But younger drivers remain more dangerous.