Year	% gross
1971	22.9730606079102
1972	24.0243396759033
1973	24.3751106262207
1974	25.118709564209
1975	24.938570022583
1976	25.5191192626953
1977	26.1593799591064
1978	26.8983402252197
1979	27.355920791626
1980	27.0976104736328
1981	25.6676292419434
1982	24.9732704162598
1983	24.6314792633057
1984	23.6367092132568
1985	23.0239391326904
1986	22.2088298797607
1987	22.0208797454834
1988	21.979040145874
1989	25.3128604888916
1990	25.4065799713135
1991	25.8793201446533
1992	27.4326591491699
1993	30.7197608947754
1994	33.7702407836914
1995	36.3214302062988
1996	39.6511192321777
1997	44.2907600402832
1998	48.2177505493164
1999	52.4957389831543
2000	54.5383415222168
2001	59.2086791992188
2002	63.0178184509277
2003	65.0038223266602
2004	68.3996734619141
2005	71.8731994628906
2006	74.6659393310547
2007	76.9792175292969
2008	78.8654403686523
2009	80.0612335205078
2010	80.4463500976562
2011	80.7510375976562
2012	77.2598114013672
2013	72.5381469726562
2014	73.4566497802734
2015	72.1444473266602
2016	73.5641021728516
2017	76.4468078613281
2018	72.0947494506836
2020	74.6230010986328
2021	72.6490020751953
