Year	% of tax revenue
1973	18.352941176470573
1974	16.412213740457997
1975	15.106732348111676
1976	14.806110458284374
1977	14.594127806563058
1978	11.519078473722102
1979	8.644729503625207
1980	7.560000000000032
1981	7.420271550363173
1982	6.8802781917536
1983	5.674015178894113
1984	4.436757407128879
1985	4.226563459884513
1986	3.794730633110488
1987	4.92742985137876
1988	5.588087572253495
1989	3.793205317577543
1990	3.6364553386795846
1991	0.8735105796548395
1992	0.49847021210766884
1993	0.08451596999683059
1994	0.02185655852874143
1995	0.004978866337799143
1996	0.0022678093808580773
1997	0.005820611174782586
1998	0.00864489186318141
1999	0.0006390270940298814
2000	0.0009884044861479028
2001	0.00016515311021722589
2002	0.0004041697791949767