Year	Percent
1977	3.79238
1978	2.86561
1979	2.70671
1980	6.30038
1981	18.48726
1982	7.90308
1983	13.70295
1984	20.05696
1985	15.69
1986	65.75043
1987	39.45178
1988	9.20246
1989	47.5919