Year	% of total
1970	70.60678340376174
1971	71.1848743848855
1972	68.17418994699995
1973	67.98556757073858
1974	63.88956180880936
1975	60.874021547152694
1976	61.35457438457864
1977	60.7818451533535
1978	59.618451194170575
1979	59.91690737876445
1980	54.46854584204601
1981	51.687543814394985
1982	51.093817285973856
1983	57.18260848603273
1984	24.82706652542373
1985	27.271775717776976
1986	28.645552130765807
1987	27.183975583161956
1988	10.896883146953245
1989	10.667272041538698