 Complete the following phrase:  Daytona International Speedway is long and a 500-mile race requires 200 laps to complete. However, the race was considered official after halfway 100 laps250 miles had been completed from 1959 to 2016. From 2017 to 2019, the race was considered official after the conclusion of Stage 2 120 laps300 miles when stage-racing was introduced. In 2020, they revised the rule in which a race is considered official at either halfway or the conclusion of Stage 2 whichever comes first, in this case halfway. The race has been shortened four times due to rain in 1965, 1966, 2003, and 2009 and once in response to the energy crisis of 1974. Since the adaptation of the greenwhitecheckered finish rule in 2004, the race has gone past 500 miles on ten occasions 2005, 2006, 