Year	% gross
1972	13.9154796600342
1973	14.2472295761108
1974	14.5828800201416
1975	15.8413496017456
1976	16.4644794464111
1977	16.9851894378662
1978	17.7699108123779
1979	17.6524200439453
1980	17.8929691314697
1981	16.3506298065186
1982	16.4901599884033
1983	16.6944198608398
1984	16.804349899292
1985	16.8123607635498
1986	16.7207508087158
1987	16.8669605255127
1988	16.8504695892334
1989	16.8706703186035
1990	16.8152599334717
1991	16.7021999359131
1992	16.5459995269775
1993	15.8636999130249
1994	15.3501596450806
1995	15.1056203842163
1996	15.135890007019
1997	14.2637300491333
1998	14.3987102508545
1999	12.2780303955078
2000	12.4426403045654
2001	12.3382596969604
2002	12.8043203353882
2003	13.6820001602173
2004	14.8328399658203
2005	15.0630502700806
2006	15.7114496231079
2007	16.3387794494629
2008	16.2974491119385
2009	16.7605991363525
2010	17.3641796112061
2011	19.7143497467041
2012	24.2553195953369
2013	26.8687591552734
2014	19.2245006561279
2015	20.6917705535889
2016	20.809009552002
2017	21.1224994659424
2018	21.1590194702148
2019	21.3356094360352
2020	21.4040699005127