Year	% of tax revenue
1978	0.1599360255897641
1979	0.1325820351342393
1980	0.1132663174288546
1981	0.09076469253460404
1982	0.09879470460383323
1983	0.1146131805157593
1984	0.12526096033402923
1985	0.0977175961471348
1986	0.10862108392407958
1987	0.10605920870607766
1988	0.047961630695443645