It's well documented that teenagers are less and less likely to have a driver's license, but a new study says that it's not just Millennials losing interest in driving. A report from the University of Michigan Transportation Research Institute (UMTRI) reveals that from 2011 to 2014, the percentage of Americans with a driver's license fell in every age range, from young to old.

Among Americans aged 16 through 44, the researchers found that the percentage with a driver's license fell continuously from 1983 through 2014. As of 2014, just 24.5 percent of American 16-year-olds and 76.7 percent of 20-24-year-olds held a driver's license, down from 31.1 and 82.0 percent in 2008, respectively.

Older drivers are also less likely to be licensed to drive than before. According to the study, the percentage of licensed drivers has fallen among Americans aged 45 to 69 years old, as well as in drivers aged 70 or older. The age range most likely to have a driver's license is now Americans 60 to 64, with 92.1 percent holding a license. In 2008, 95.9 percent of that demographic had a driver's license.

The UMTRI researchers don't offer an explanation for why Americans are less likely to have a license than before, but the availability of public transport and smartphone-enabled ride services, like Uber and Lyft, likely mean fewer people need to drive themselves.

Changing economics and lilfestyles also play a role. A 2013 study found that teenagers were less likely to drive than in the past because they couldn't find jobs to afford driver's ed classes or a car. And a separate 2013 study found that 22 percent of Americans aged 18 to 22 said they never plan to get a driver's license at all. But in 2014, only 8 percent of Gen Y respondents surveyed by Deloitte said they "do not expect to ever purchase or lease a vehicle. "