Despite a focus on vehicle safety technology with advancements like crash-avoidance systems and backup cameras, last year saw the most number of deaths from car crashes in nearly a decade.

According to preliminary data released Feb. 15 from the National Safety Council (NSC), as many as 40,000 people died in motor vehicle crashes in 2016 with an additional 4.6 million people suffering from injuries serious enough to need medical attention.

The numbers continue an alarming trend upward over the last two years. The NSC said deaths are estimated to have increased 6 percent from 2015 and 14 percent from 2014. The nonprofit says the two-year jump is the most dramatic escalation in 53 years.

“Our complacency is killing us. Americans believe there is nothing we can do to stop crashes from happening, but that isn’t true,” said NSC President and CEO Deborah Hersman. “The U.S. lags the rest of the developed world in addressing highway fatalities. We know what needs to be done; we just haven’t done it.”

The reason for the dramatic upswing in deaths is unclear. With an improving economy and low gasoline prices, some believe that Americans are driving more miles for work and pleasure. However, experts say that does not account for such a sharp increase in traffic fatalities

The NSC released a driver safety survey taken by more than 2,000 people that may offer some clues. Sixty-four percent of people said they are comfortable speeding and 47 percent said they are comfortable texting while driving, either manually or through a voice command system.

Speeding and Lack of Seatbelts Still Major Issues

While the prevalence of electronic devices and cellphones may play a role in the increase, organizations like the National Highway Traffic Safety Administration (NHTSA) and Governors Highway Safety Association (GHSA) contend a lack of enforcement of existing laws is partly to blame.

“According to NHTSA, 94 percent of traffic crashes are related to human choices,” the GHSA, a nonprofit association, said in a news release. “GHSA continues to hear from state agencies that the three predominant factors contributing to traffic deaths are still belts, booze and speed.”

In only 18 states can a driver be pulled over if front or back passengers are not wearing seatbelts. The NHTSA reports nearly half of people killed in crashes were not wearing seat belts.

“In 2015 alone, seat belts saved an estimated 13,941 lives – and could have saved an additional 2,814 people if they had been wearing their seat belts,” the NHTSA wrote on its site. “In total, seat belts have saved 344,448 lives since 1975, when NHTSA first began recording this data. If everyone had been wearing a seat belt since, an additional 381,787 lives could have been saved.”

National campaigns like the “Click It Or Ticket” and “Buckle Up” campaigns are aimed at getting more people to wear seat belts. Figures from the U.S. Department of Transportation indicate that advertising and enforcement can increase seat belt usage.

Technology May Help Reduce Deaths, Experts Say

While an emphasis on enforcing existing laws are a priority, some say that new safety technology can have a major impact in saving lives. Technology like lane departure warning systems can prevent drifting into oncoming traffic, but some see the self-driving car movement as a different way to prevent accidents.

According to Mark Rosekind, administrator of the NHTSA, self-driving cars could potentially cut the number of deaths from accidents in half. The NHTSA has already begun releasing guidelines on automated car technology.

“We envision in the future, you can take your hands off the wheel, and your commute becomes restful or productive instead of frustrating and exhausting,” said Jeffrey Zients, director of the National Economic Council, according to the New York Times. He also added that self-driving cars “will save time, money and lives.”