Year	% gross
1980	16.2546997070313
1981	16.2231502532959
1982	15.8487396240234
1983	15.7199096679688
1984	15.5929803848267
1985	15.5207796096802
1986	15.8407497406006
1987	15.6298599243164
1988	15.707989692688
1989	15.8013296127319
1990	15.7433795928955
1991	15.9058504104614
1992	15.9575996398926
1993	15.9420795440674
1994	15.6595401763916
1995	15.6919097900391
1996	15.7689695358276
1997	15.4418001174927
1998	15.5539197921753
1999	13.9482097625732
2000	14.8255596160889
2001	15.4934997558594
2002	17.3606090545654
2003	18.4885196685791
2004	19.9828395843506
2005	20.791540145874
2006	21.7925491333008
2007	19.7277908325195
2008	19.2916107177734
2009	20.7065601348877
2010	20.4192295074463
2011	22.5050506591797
2012	24.7257194519043
2013	27.0498600006104
2014	20.212739944458
2015	21.6062602996826
2016	22.9795799255371
2017	23.439769744873
2018	23.4002094268799
2019	23.4582901000977
2020	24.1217498779297
