Year	Number
1961	65.40697674418605
1962	62.77777777777778
1963	78.88888888888889
1964	90.52631578947368
1965	92.23300970873787
1966	100.97087378640776
1967	100.74074074074073
1968	99.5575221238938
1969	102.17391304347827
1970	106.38297872340425
1971	112.5
1972	118.75
1973	125
1974	126.58227848101266
1975	128.2051282051282
1976	129.87012987012986
1977	131.57894736842107
1978	133.92857142857142
1979	136.36363636363635
1980	142.85714285714286
1981	142.85714285714286
1982	144.23076923076923
1983	144.23076923076923
1984	144.23076923076923
1985	147.05882352941177
1986	150
1987	159.5744680851064
1988	161.29032258064515
1989	163.04347826086956
1990	174.86338797814207
1991	187.84530386740332
1992	200
1993	211.11111111111111
1994	222.22222222222223
1995	250
1996	273.22404371584696
1997	303.2432432432432
1998	300
1999	640