Year	% of total
1970	9.080264190292613
1971	9.231229735624813
1972	8.337609380396529
1973	7.269247956571561
1974	5.863825681606792
1975	5.83440193604913
1976	6.176004135720136
1977	5.855912969041789
1978	6.248207205134782
1979	6.904611456250771
1980	7.421622414587596
1981	7.405749992618481
1982	7.023073727634093
1983	6.494485290359091
1984	6.1627544410898745
1985	6.228022130806176
1986	5.421132775995983
1987	6.009851308384363
1988	5.929017484051698
1989	6.82876298307885