Year	% gross
1971	4.86162996292114
1972	5.32870006561279
1973	5.82330989837646
1974	6.54148006439209
1975	7.69930982589722
1976	8.70306968688965
1977	9.57297039031982
1978	9.73806953430176
1979	9.46131038665771
1980	10.229829788208
1981	9.68222045898438
1982	9.51543998718262
1983	9.23616981506348
1984	8.77136039733887
1985	9.38222980499268
1986	10.7099800109863
1987	10.3435001373291
1988	10.7636995315552
1989	11.9087200164795
1999	11.6270198822021
2000	12.054630279541
2002	12.6024503707886
2004	15.4530696868896
2005	15.499340057373