Year	Number
1961	16.444917731562683
1962	17.563128935751795
1963	18.5876189681082
1964	19.834578663345788
1965	21.009272614877396
1966	22.732335465706065
1967	25.83788800659998
1968	26.939722112935623
1969	28.380539200495818
1970	29.558369363804818
1971	29.992211215849178
1972	31.961424391409064
1973	34.84603140291234
1974	38.03529133112269
1975	41.836310594253284
1976	44.764547932029494
1977	47.62046847724597
1978	52.893151586175705
1979	57.07107050452781
1980	63.817231710425695
1981	68.14214020968355
1982	71.99397126705217
1983	78.51913268843653
1984	85.05211226297153
1985	94.10107782674933
1986	100.70917395191533
1987	105.1749148467241
1988	108.69604352522303
1989	110.1186050343838
1990	116.46354916740546
1991	116.22237147864217
1992	115.91571295488444
1993	118.87093277867407
1994	121.03873123589743
1995	127.50494043249958
1996	127.9255798284035
1997	142.52885092828737
1998	131.3932129116271
1999	134.4344415895524
2000	159.2618260740887
2001	168.88973224801737