Studies of accident outcomes suggest that fatality rates among car occupants are reduced by between 30 and 50 percent if seat belts are worn. The US National Highway Traffic Safety Administration (NHTSA) estimates that death risks for a driver wearing a lap-shoulder seat belt are reduced by 48 percent. The same study indicated that in 2007, an estimated 15,147 lives were saved by seat belts in the United States and that if seat belt use were increased to 100 percent, an additional 5024 lives would have been saved.