In the Grand National horse race, how many of the fences are jumped only once by a horse completing the course?

The Grand National is a National Hunt horse race held annually at Aintree Racecourse near Liverpool, England. First run in 1839, it is a handicap steeplechase over 4 miles 514 yards (6.907 metres) with horses jumping 30 fences over two laps. It is the most valuable jump race in Europe, with a prize fund of £1 million in 2017. An event that is prominent in British culture, the race is popular amongst many people who do not normally watch or bet on horse racing at other times of the year.

The race consists of two laps, 16 fences are jumped on the first lap, but only 14 are jumped on the second lap. Horses completing the race cover a distance of 4 miles 514 yards (6.907 km), the longest of any National Hunt race in Britain.