Year	% gross
1971	28.8424491882324
1972	31.0899105072021
1975	31.4302101135254
1976	33.1828193664551
1977	34.1780281066895
1978	34.8027610778809
1979	34.7144393920898
1980	35.0474700927734
1981	34.5517883300781
1982	34.3343696594238
1983	34.1813087463379
1984	34.3573799133301
1985	35.4363403320312
1986	37.0385894775391
1987	36.325008392334
1988	36.9452514648438
1989	36.745189666748
1990	38.6055297851562
1991	42.7423782348633
1992	44.6706085205078
1993	47.7917785644531
1994	53.0072708129883
1995	51.6438293457031
1996	52.3082389831543
1997	50.2286605834961
1998	49.5927200317383
1999	49.6796188354492
2000	50.7199096679688
2001	51.6215591430664
2002	52.5698394775391
2003	52.8644599914551
2004	54.7508392333984
2005	56.6634902954102
2006	57.5001907348633
2007	57.661979675293
2008	58.0879707336426
2009	58.2571792602539
2010	60.3694305419922
2011	71.637451171875
2012	72.6818389892578
2015	75.2541198730469
2016	75.4073867797852
2017	78.0011978149414
2018	78.8291091918945
2020	79.4261322021484
2021	82.2641220092773
