BOSTON — Seat belts saved an estimated 115 lives in Massachusetts in 2016, and 45 more could have been saved if 100 percent of drivers and passengers buckled up, according to data released Wednesday.

A new study, conducted by the University of Massachusetts Traffic Safety Research Program, found seat belt usage rose nearly 8 percent from 73.7 percent in 2017 to 81.6 percent in 2018, representing the largest year-to-year hike in state history.

The national seat belt use rate was 90.1 percent in 2016, according to the National Highway Traffic Safety Administration.

Under state law, all occupants of private or commercial motor vehicles must be restrained by seat belts. Massachusetts does not have primary enforcement of its seat belt law, so drivers can only be cited for violations if police pull them over for another reason.

Lawmakers have for years filed bills to make not wearing a seat belt a primary offense, for which police could stop drivers, but concerns about privacy and the potential for overzealous enforcement or racial profiling have stymied the efforts.

For the survey, 28,265 drivers and front-seat passengers in 24,145 vehicles were observed at 147 locations across the state.

The biggest sample size was in Dartmouth, where 1,166 of the 1,467 occupants observed wore their seat belts, for a rate of 79.48 percent.

The usage rates varied regionally, ranging from 77.75 percent in Barnstable and Plymouth counties to 85.06 percent in Norfolk and Suffolk counties.

Occupants of pickup trucks and commercial vehicles had the lowest use rates among different types of vehicles, at 69 percent and 54.1 percent respectively, according to the study.

--State House News Service