Year	% gross
1970	4.28086996078491
1971	4.27867984771729
1972	4.48126983642578
1973	4.67493009567261
1974	4.76240015029907
1975	5.12033987045288
1976	5.84573984146118
1977	6.11042976379395
1978	6.0878701210022
1979	6.0346999168396
1980	5.94195985794067
1981	5.92936992645264
1982	6.1048698425293
1983	5.70731019973755
1984	5.74458980560303
1985	5.96049022674561
1986	6.19139003753662
1987	6.46705007553101
1988	6.69792985916138
1989	7.01079988479614
1990	7.529709815979
1991	8.43196964263916
1992	8.68255996704102
1993	8.93496036529541
1994	9.27624034881592
1995	9.39925956726074
1996	9.76412010192871
1997	10.0908098220825
1998	10.0192499160767
1999	10.0236902236938
2000	12.2812404632568
2001	13.2411699295044
2002	14.2308702468872
2003	15.0830297470093
2004	16.2319793701172
2005	15.7237901687622
2006	15.823769569397
2007	17.1103401184082
2008	18.6484203338623
2009	19.244909286499
2010	20.7520599365234
2011	20.8052597045898
2012	22.2190494537354
2013	21.7770195007324
2014	22.1645908355713
2015	22.3489398956299
2016	22.4792499542236