Year	% of tax revenue
1972	8.068406051304535
1973	7.08444275389882
1974	6.263945128501784
1975	5.021486551010666
1976	4.242336190614547
1977	3.5607147515325446
1978	2.423167848699758
1979	2.3343332424325056
1980	2.46919839780966
1981	2.28099636160089
1982	2.3104399330831527
1983	2.414280210607425
1984	2.403380238012167
1985	2.4663332050788833
1986	2.4987120041215842
1987	2.688906463440941
1988	2.823860475769771
1989	2.9275759798450056
1990	2.73558017218582
1991	2.7479383680555562
1992	2.6109467455621287
1993	2.449261882616675
1994	2.3915031300555705
1995	0.2150718801342542
1996	-0.0007391580820495038
1997	0.001067749707604652
1998	0.0012879446486846865
1999	0.012601101269929407
2000	-0.00864000748324615
2001	-0.009502019584537977
2002	-0.0024034154004318954
2003	-0.0021040937247508752
2004	0.006179557553089692
2005	0.0022059530187541485
2006	0.00010433557540548157
2007	-0.010623003073043409
2008	-0.02695617643672504
2009	9.633967055686257E-05
2010	0.00012030877648514166
2011	0.00010144628159433484
2012	8.472423290982109E-05