In 2013, Airbus said, for long haul flights, there should be an industry standard for a minimum seat width of 18 inches in economy cabins, but its rival Boeing argued it was up for airlines to decide.[17] People have been getting wider: the weight of the average American male in his 40s had increased by 10 percent in the 30 years from the 1970 introduction of the Boeing 747.[17] The narrower 17-inch-wide seat favoured by Boeing is a legacy from the 1950s when passenger jets were first introduced.[17] In the 1970s and 1980s with the introduction of the Boeing 747 and the first Airbus jets, 18 inches become standard for long-haul flights.[18] Seats were widened to 18.5 inches with the Boeing 777 in the 1990s and A380 superjumbo in the 2000s.[18] Many airlines are adopting lighter 17-inch-wide seats on their Boeing 777 and 787 and 18-inch seats for A350s.[18] Although for almost 20 years, the standard setup in the back of a Boeing 777 was nine seats per row, in 2012 nearly 70% of the biggest version of that plane were delivered with 10-abreast seating.[18] When Airbus introduced its A380, it offered 10-abreast seating, giving each passenger up to 19 inches of hip space.[18] In 2013, ten airlines fly Airbus A330 with nine 16.7-inch seats in each row, rather than the eight it was designed for.[18] A research report commissioned by Airbus concluded that an extra inch in seat width improves sleep quality by 53 percent.[17]