Year	% of tax revenue
1975	46.097337006427914
1976	34.33734939759036
1977	26.587112171837706
1978	34.07275953859805
1979	35.679702048417134
1981	33.37985578041405
1982	35.03694581280788
1983	30.652639087018546
1984	34.84302624807
1985	32.2094468614046
1986	26.775045157704596
1987	25.706289978678036
1988	27.865143115737073
1989	27.974849849849846
1990	23.952993138260116
1991	20.639324487334136
1992	19.221193495681945
1993	18.638829750703938
1994	19.75519755197552
1995	20.450057022057802
1996	20.606590114827757
1997	19.929328621908127
2002	14.198259911027126
2003	14.642241997990526
2004	13.613618085961935
2005	10.116209694876952
2006	9.770717404266156
2007	8.950306011684162
2008	9.73867180581259
2009	8.268457757407518
2010	8.054793877772466
2011	7.005014775678338
2015	6.849001657095605