Year	% gross
1976	21.584659576416
1977	21.7360000610352
1978	21.828950881958
1979	22.1977500915527
1980	22.250129699707
1981	22.3695602416992
1982	22.29833984375
1983	22.6195392608643
1984	22.9467697143555
1985	23.0683994293213
1986	23.31715965271
1987	23.2437705993652
1988	23.6309509277344
1989	23.845630645752
1990	24.0508403778076
1991	25.4951992034912
1992	25.4144706726074
1993	26.3518009185791
1994	25.9771709442139
1995	26.0530605316162
1996	26.547830581665
1997	27.3160800933838
1998	26.9454097747803
1999	26.8696308135986
2000	26.7833194732666
2001	28.4745197296143
2002	29.4704608917236
2003	29.5159893035889
2004	30.0593395233154
2005	30.5098400115967
2006	30.9149894714355
2007	32.0333518981934
2008	34.2313804626465
2009	35.1831703186035
2010	35.2083396911621
2011	36.4793395996094
2012	36.1650199890137
2013	36.5267105102539
2014	37.8403282165527
2015	38.6457214355469
2016	38.9104690551758
2017	39.0863800048828
2018	39.5857887268066
2019	39.8862495422363
2020	40.050968170166