Year	Percent
1974	69.20464
1975	70.3104
1976	71.26572
1977	74.02082
1978	74.43075
1979	69.30527
1980	69.9736
1981	76.19699
1982	80.42787
1983	74.53455
1984	77.89628
1985	75.84951
1986	74.51909
1987	73.73841
1988	75.56976
1991	82.71798