Year	Number of
1963	22090
1964	22170
1965	22460
1966	22950
1967	23620
1968	24160
1969	24490
1970	24440
1971	24060
1972	23520
1973	23020
1974	22810
1975	22890
1976	23130
1977	23600
1978	24230
1979	24780
1980	25260
1981	25410
1982	25360
1983	25350
1984	25220
1985	25270
1986	25380
1987	25590
1988	25890
1989	26280
1990	26700
1991	27130
1992	27720
1993	28280
1994	28620
1995	28620
1996	28190
1997	27270
1998	26050
1999	24960
2000	24150
2001	23820
2002	23810
2003	23960
2004	24080
2005	24000
2006	23640
2007	23140
2008	22540
2009	21860
2010	21150
2011	20490
2012	19790
2013	19240
2014	18690
2015	18240