Carriers are evaluated only on inspections and crashes associated with their own U.S. DOT number, so only violations that a driver receives while working for a motor carrier apply to that carrier’s SMS evaluation. Therefore, the driver’s violation history before the driver is hired and after the driver’s employment is terminated will not impact a motor carrier’s SMS results. However, even if a motor carrier terminates a driver, all of the driver’s crashes and inspection results that he or she received while operating for that carrier still apply to the carrier’s SMS evaluation for 24 months from the date of occurrence. Because the data is time-weighted, the effect of those occurrences on the motor carrier’s percentile rank will diminish over the course of the 24 months.