The fatality rate of back seat passengers not wearing seat belts was about four times higher than that of those wearing a seat belt in traffic accidents in 2005, according to the National Police Agency...less than 10 percent of back seat passengers, who are not legally required to wear seat belts, used them...An agency survey of accidents involving fatalities and injuries in which back seat passengers had been wearing seat belts revealed that 25 such passengers died in 23,035 accidents--a fatality rate of 0.11 percent.