Year	% gross
1971	7.54186010360718
1972	8.32701015472412
1973	9.17945003509521
1974	9.7544002532959
1975	10.8359403610229
1976	11.6257400512695
1977	12.9329795837402
1978	13.048210144043
1979	12.6908502578735
1980	14.0170402526855
1981	13.0970897674561
1982	13.0503396987915
1983	12.5582599639893
1984	11.8485698699951
1985	13.2732801437378
1986	13.6092796325684
1987	12.6142501831055
1988	12.9860095977783
1989	14.7555503845215
1999	15.0541000366211
2000	15.6398496627808
2002	16.3482398986816
2004	19.4095001220703
2005	19.4847507476807