Year	% of tax revenue
1972	41.65268456375843
1973	38.27512473271567
1974	42.72363150867826
1975	39.57064113722084
1976	41.60804020100506
1977	40.25572282944944
1978	39.69283276450514
1980	42.069370958259796
1981	38.06898043031676
1982	35.32597154385223
1983	32.07107162687393
1984	32.869666861484475
1985	36.806903991369936
1986	39.06491898028698
1987	41.128307538691985
1988	41.55965643337007
1989	42.64416527924937
1990	42.8290499762665
1991	42.62325015216072
1992	41.84175968483252
1993	39.22484472049695
1994	32.26135535584165
1995	6.153139800882817
1996	6.537620574377153
1997	6.111310487267188
1998	6.435531214257695
1999	6.33304238192222
2000	5.599273223431849
2001	5.283161251251114
2002	4.327483920274903
2003	3.7917365932231597
2004	1.111363807346312
2006	0.17007254657064652
2007	0.010684358935245705
2008	0.05925628060377716
2009	0.004605702719698161