Year	Number
1961	247.66125807080797
1962	258.4984197028446
1963	266.7971730843724
1964	277.41497383225663
1965	286.3331315083252
1966	313.3922335304473
1967	321.4158146989326
1968	321.37466059620243
1969	323.15316657343647
1970	328.75233557935815
1971	338.2872038605399
1972	343.71866285726514
1973	352.70415112337906
1974	363.3111300343943
1975	379.106876564642
1976	386.4823007190663
1977	394.6989118572236
1978	399.4457724240947
1979	403.4379601313456
1980	416.8918053042771
1981	419.376014235672
1982	428.17833487947007
1983	434.3021036904664
1984	439.0237417787395
1985	450.0549069269504
1986	455.4960031457992
1987	466.58758398048514
1992	453.9296735266865
1993	455.3624217500597
1994	462.19010840557894
1995	467.3069297991629
1996	471.11250724048745
1997	473.8841640377077
1998	476.9937578465888
2000	486.55471936887966