More than 15,000 passenger vehicle occupants died in traffic crashes between the nighttime hours of 6 p.m. and 5:59 a.m. during 2005, according to the National Highway Traffic Safety Administration -- and 59 percent of those passenger vehicle occupants killed were not wearing their seat belts at the time of the fatal crash.The proportion of unbuckled deaths at night is considerably higher than the nearly as alarming 44 percent of passenger vehicle occupants who were not wearing their seat belts and were killed during daytime hours across the nation that same year.That's why the Silver Lake Police Department is joining with state and local law enforcement and highway safety officials through Memorial Day to launch an aggressive national "Click It or Ticket" seat belt enforcement mobilization to crack down on law seat belt use and to reduce highway fatalities -- with a new emphasis this year on convincing more motorists to buckle up day and night.Chief Gary DeMoss says regular seat belt use is the single most effective way to protect people and reduce fatalities in motor vehicle crashes. He said that in 2005, 77 percent of passenger vehicle occupants in a serious crash who were buckled up, survived the crash and that when worn correctly, seat belts have proven to reduce the risk of fatal injury to front-seat passenger car occupants by 45 percent -- and by 60 percent in pickup trucks, SUVs and mini-vans.Yet nearly one in five Americans -- 19 percent nationally -- still fail to regularly wear their seat belts when driving or riding in a motor vehicle, according to NHTSA's observational seat belt studies. Stepped-up law enforcement activities will be conducted through the national "Click It or Ticket" enforcement mobilization, which runs May 21 to June 3. The mobilization is being supported by a projected $10 million in paid national advertising and additional advertising in each state, to encourage all motorists, but especially motorists at night, to always buckle up."Seat belts clearly save lives," DeMoss says, "But unfortunately, too many folks still need a tough reminder, so we are going to be in out in force, buckling down on those who are not buckled up."