Year	% gross
1970	11.526909828186
1971	11.4324703216553
1972	11.3374099731445
1973	11.2417402267456
1974	11.0373001098633
1975	11.4649095535278
1976	12.0446996688843
1977	12.4141702651978
1978	12.4980602264404
1979	12.9343099594116
1980	13.3006401062012
1981	14.0203104019165
1982	13.9349002838135
1983	14.1338396072388
1984	14.3663597106934
1985	14.8753595352173
1986	14.588680267334
1987	14.6974000930786
1988	14.5964298248291
1989	14.9535703659058
1990	14.7626399993896
1991	14.8855800628662
1992	15.0040397644043
1993	15.0891895294189
1994	15.2747297286987
1995	15.3916902542114
1996	15.6576700210571
1997	15.7819299697876
1998	15.9634504318237
1999	15.5783796310425
2000	15.8864498138428
2001	15.6733598709106
2002	15.9110803604126
2003	16.0599899291992
2004	16.5141506195068
2005	17.2101497650146
2006	19.0711898803711
2007	18.883129119873
2008	20.4102306365967
2009	23.5901908874512
2010	23.9722595214844
2011	23.5586490631104
2012	24.3136806488037
2013	23.5894508361816
2014	26.4449501037598
2015	27.3764801025391
2016	27.0494499206543
2017	27.3526496887207
2018	27.3670902252197
2019	27.8929500579834
2020	28.3363704681396