Year	% of total
1960	83.25062034739453
1961	83.91304347826087
1962	85.97014925373134
1963	88.95599654874893
1964	89.58333333333334
1965	90.54157131960336
1966	92.1220723917672
1967	94.43099273607749
1968	94.26713947990542
1969	96.2665406427221
1970	96.72632038411174
1971	96.31705364291435
1972	97.23538704581361
1973	97.39644970414201
1974	97.01236263736264
1975	97.13810316139768
1976	96.59923776018762
1977	96.16078330327235
1978	95.90316573556798
1979	95.79870729455216
1980	95.44454225352112
1981	95.33058661958015
1982	81.61176251628513
1983	64.09003664281975
1984	55.33311453889071
1985	47.27533460803059
1986	45.148401826484026
1987	38.547341115434506
1988	32.49999999999999
1989	30.099081681971963