Dragan Radovanovic/Business Insider
Dragan Radovanovic/Business Insider
The study, authored by Professor Michael Sivak and researcher Brandon Schoettle of the university's
For example, the number of drivers 20-24 has shrunk from 91.8% in 1983 to 76.7% in 2014.
Among 45-69 year olds, the number with licenses increased until a peak sometime in the past ten years, and has since shown a small decrease.
But after increasing significantly from 55% in 1983 to 79.2% in 2011, drivers over 70 have held steady, posting only a .2% decrease in 2014 and maintaining a higher proportion on the road than drivers under 25.
Sivak, who published a similar study in 2011, would not speculate on possible reasons for the trend, but expects his team to test possible reasons in the near future.