Year	% gross
1971	2.10351991653442
1972	2.00540995597839
1973	2.12649011611938
1974	2.18479990959167
1975	4.39342021942139
1976	5.37769985198975
1977	6.13783979415894
1978	6.58081007003784
1979	7.77677011489868
1980	8.02783966064453
1981	8.50607013702393
1982	8.80270957946777
1983	8.34078979492188
1984	7.82975006103516
1985	8.07061958312988
1986	8.01700973510742
1987	7.75589990615845
1988	7.28166007995605
1989	7.97275018692017
1991	7.79722023010254
1992	6.96271991729736
1993	7.80067014694214
1996	6.77089023590088
1998	5.36641979217529
1999	5.06452989578247
2000	5.23192977905273
2003	3.55088996887207
2004	5.86493015289307
2007	6.64256000518799
2011	3.8199999332428