Year	Number
1961	41.718170580964156
1962	43.333333333333336
1963	44.354838709677416
1964	45.662100456621005
1965	45.62308560374013
1966	48.223758238225365
1967	62.68846214886526
1968	63.75140156975812
1969	64.17455478902615
1970	64.34058898847631
1971	63.479623824451416
1972	62.51920122887865
1973	62.960687960687956
1974	63.11124694376527
1975	60.62819576333089
1976	58.93965031020869
1977	60.8342989571263
1978	61.15351131746954
1979	66.9690330119778
1980	68.36363636363636
1981	69.71677559912854
1982	71.50123528556895
1983	76.27275485436893
1984	88.67534345625452
1985	108.98697539797395
1986	118.62638151284628
1987	126.28518885273729
1988	129.1367413040417
1989	111.94978257820172
1990	129.11453184578448
1991	135.20247933884298
1992	121.11346204707749
1993	128.15611310234968
1994	121.12745753644509
1995	121.29804495278627
1996	122.35474006116208
1997	120.81830065359478
1998	121.13301135621981
1999	122.84504105304315
2000	124.92430174889063
2001	128.14980878280363
2002	129.4554127467868
2003	130.33570105414663
2004	130.53383157613774
2005	133.3084808946878
2006	137.0321285140562
2007	138.65042174320524
2008	139.5767125116838