Year	% gross
1971	16.2816390991211
1972	17.5334796905518
1973	18.6813507080078
1974	19.4405307769775
1975	19.88623046875
1976	22.0252895355225
1977	22.7852802276611
1978	22.7809791564941
1979	23.3337898254395
1980	24.10791015625
1981	24.9204006195068
1982	24.4557991027832
1983	24.6099300384521
1984	25.5455303192139
1985	27.2346897125244
1986	28.3953990936279
1987	29.6784801483154
1988	31.5298690795898
1989	33.1247482299805
1990	34.9733390808105
1991	37.2959785461426
1992	40.5758018493652
1993	42.5735015869141
1994	44.9975509643555
1995	47.7225799560547
1996	50.2559204101562
1997	51.6062393188477
1998	53.5982284545898
2013	73.6377334594727
2014	73.9486236572266
2015	74.9949417114258
2016	75.2818908691406
2017	76.1750106811523
2018	77.8700866699219
2019	77.816650390625
2020	79.6415100097656
2021	83.3328018188477