Year	% gross
1971	7.40331983566284
1972	7.41958999633789
1973	7.48130989074707
1974	7.5601601600647
1975	7.68305015563965
1976	7.79648017883301
1977	7.86661005020142
1978	7.94229984283447
1979	8.07262992858887
1980	8.10554981231689
1981	8.03820991516113
1982	8.1290397644043
1983	8.02525043487549
1984	7.93424987792969
1985	7.99340009689331
1986	8.01550006866455
1987	8.12003993988037
1988	8.25475978851318
1989	8.30603981018066
1990	8.31830024719238
1991	8.25316047668457
1992	8.13018035888672
1993	8.06167030334473
1994	7.83871984481812
1995	7.75795984268188
1996	7.76044988632202
1997	7.70236015319824
1998	7.9684100151062
1999	8.08765983581543
2000	8.30986022949219
2001	8.42897033691406
2002	8.66154003143311
2003	9.03835964202881
2004	9.27266979217529
2005	9.55107975006104
2006	9.94631958007813
2007	10.2035799026489
2008	10.8940801620483
2009	11.6868000030518
2010	11.4874095916748
2011	11.947699546814
2012	14.311240196228
2013	15.3027296066284
2014	16.163890838623
2015	17.3955097198486
2016	18.0468902587891
2017	18.9650192260742
2018	19.3886699676514
2019	19.8259296417236
2020	20.1464595794678