Year	Number
1961	6177
1962	6479
1963	7187
1964	7340
1965	7940
1966	8640
1967	9340
1968	9840
1969	9860
1970	9882
1971	10200
1972	10500
1973	10800
1974	11100
1975	11400
1976	11700
1977	12000
1978	12300
1979	12700
1980	13200
1981	13500
1982	13800
1983	14000
1984	14000
1985	13200
1986	13200
1987	13000
1988	12000
1989	11400
1990	11467
1991	11147
1992	10852
1993	10515
1994	10434
1995	10519
1996	10000
1997	9500
1998	8925
1999	9051
2000	9019
2001	9019
2002	10900
2003	10789
2004	10750
2005	10928
2006	11144
2007	11403
2008	11525
2009	11432