Year	% of total
1960	79.14893617021276
1961	74.79338842975206
1962	66.23376623376623
1963	70.41420118343196
1964	67.33333333333334
1965	64.28571428571428
1966	60.679611650485434
1967	58.2089552238806
1968	50.199203187250994
1969	49.88235294117647
1970	44.257274119448695
1971	37.87878787878788
1972	18.9247311827957
1973	10.578279266572638
1974	11.989459815546772
1975	10.72463768115942
1976	8.282208588957054
1977	11.643835616438357
1978	7.600950118764844
1979	14.285714285714285
1980	15.934065934065933
1981	15.526315789473685
1982	13.623188405797102
1983	22.22222222222222
1984	22.796352583586625
1985	32.241813602015114
1986	33.15926892950392
1987	28.140703517587944
1988	29.927007299270077
1989	33.4075723830735