Year	Number
1961	1
1962	1
1963	2
1964	3
1965	4
1966	5
1967	7.5
1968	9.090909090909092
1969	11.363636363636363
1970	13.636363636363635
1971	15.909090909090908
1972	17.391304347826086
1973	21.73913043478261
1974	26.08695652173913
1975	30
1976	32.608695652173914
1977	36.52173913043478
1978	38.26086956521739
1979	40
1980	41.30434782608695
1981	47.391304347826086
1982	46.52173913043478
1983	37.77777777777778
1984	38.148148148148145
1985	43.103448275862064
1986	39.0625
1987	39.39393939393939
1988	41.515151515151516
1989	40
1990	41.14285714285714
1991	42
1992	42.857142857142854
1993	51.724137931034484
1994	53.103448275862064
1995	56.785714285714285
1996	58.214285714285715
1997	57.58620689655173
1998	55.16129032258065
1999	56.774193548387096
2000	58.06451612903226
2001	59.354838709677416
2002	60.64516129032258
2003	62.25806451612903
2004	69.3103448275862