Year	% gross
1971	2.32179999351501
1972	2.23177003860474
1973	2.33867001533508
1974	2.39630007743835
1975	4.54804992675781
1976	5.6257700920105
1977	6.36910009384155
1978	6.78787994384766
1979	7.99768018722534
1980	8.26681041717529
1981	8.626540184021
1982	8.86182975769043
1983	8.4396800994873
1984	7.91298007965088
1985	8.17782974243164
1986	8.21076011657715
1987	7.93811988830566
1988	7.33622980117798
1989	8.12269973754883
1991	7.9510498046875
1992	7.03690004348755
1993	7.89045000076294
1996	6.79971981048584
1998	5.29811000823975
1999	5.06584978103638
2000	5.19385004043579
2003	3.54130005836487
2004	5.8138599395752
2007	6.64288997650146
2011	4.07999992370605