Year % gross 1971 9.10976028442383 1972 10.0607099533081 1973 10.9632301330566 1974 10.7057695388794 1975 11.3384504318237 1976 12.3316097259521 1977 12.315239906311 1978 13.1392602920532 1979 14.4294204711914 1980 16.3870506286621 1981 18.0648002624512 1983 19.0016002655029 1984 19.3051490783691 1985 19.9326305389404 1987 19.7394104003906 1999 23.0311298370361 2014 38.4756011962891 2015 41.6637382507324 2016 43.8949584960938 2017 46.8549613952637 2018 49.0457992553711 2019 52.2111511230469 2020 54.652530670166 2021 57.2815093994141 2022 55.0669403076172