Year	Percent
1974	67.98804
1975	69.60117
1976	70.51772
1977	72.43759
1978	74.49121
1979	67.96523
1980	68.04034
1981	74.23994
1982	76.79476
1983	71.67524
1984	75.10009
1985	73.31643
1986	72.09045
1987	71.35023
1988	73.08248
1991	79.33482