Year	% of tax revenue
1973	22.350064720264633
1974	23.01725809579213
1975	30.644101215905355
1976	30.77243968574011
1977	36.80096940321115
1978	39.529284591194966
1979	41.114313160422675
1980	38.78706458113425
1981	36.04058217358971
1982	35.71863062361615
1983	38.863494924783794
1984	37.83415019479004
1985	39.30430301468694
1986	40.89840312738918
1988	42.7183920321054
1989	40.14708530378991
1997	27.82368700856745
1998	21.686136720239638
1999	16.877990523385215
2000	15.97317209649341