Year	% gross
1971	26.6201992034912
1972	27.8127994537354
1973	31.442440032959
1974	33.7840881347656
1975	37.3610992431641
1976	37.0673217773438
1977	38.2074089050293
1978	42.6346282958984
1979	46.6576309204102
1980	50.3548011779785
1981	51.5805587768555
1982	53.4055480957031
1983	49.3962783813477
1984	47.6390800476074
1985	48.643180847168
1986	50.1300582885742
1987	47.9981994628906
1988	46.4024314880371
1989	45.6065483093262
1993	42.5191917419434
1996	38.8428916931152
1999	34.1383514404297
2000	36.8089714050293
2001	36.6971702575684
2003	40.4639091491699
2004	45.2345199584961
2007	50.4981002807617