Year	Number
1961	0.1276595744680851
1962	0.2127659574468085
1963	0.425531914893617
1964	0.5106382978723404
1965	0.5106382978723404
1966	0.5106382978723404
1967	0.4897959183673469
1968	0.5306122448979592
1969	0.5306122448979592
1970	0.5306122448979592
1971	0.5306122448979592
1972	0.5714285714285714
1973	0.5599999999999999
1974	0.5490196078431373
1975	0.5490196078431373
1976	0.5882352941176471
1977	0.5882352941176471
1978	0.5882352941176471
1979	0.6274509803921569
1980	0.6274509803921569
1981	0.622568093385214
1982	0.6296296296296297
1983	0.6071428571428571
1984	0.5964912280701754
1985	0.6206896551724138
1986	0.72
1987	0.75
1988	0.826086956521739
1989	0.7916666666666667
1990	0.76
1991	0.76
1992	0.76
1993	0.7037037037037037
1994	0.6785714285714286
1995	0.6785714285714286
1996	0.7037037037037037