Year	% of tax revenue
1972	3.499743764947045
1979	0.10860429317492847
1980	0.10056755078661314
1981	0.08816701582961926
1982	0.08943429145316063
1983	0.08883758932392649
1984	0.09235222236613151
1985	0.08196518948277991
1986	0.07713933077345035
1987	0.06593242548391912
1988	0.0673592785425037
1989	0.06821784749435071
1990	0.0699930400179308