Year	Number of
1954	24200
1955	24230
1956	24160
1957	24060
1958	24040
1959	24080
1960	24240
1961	24530
1962	24880
1963	25190
1964	25430
1965	25460
1966	25290
1967	25020
1968	24610
1969	24120
1970	23520
1971	22920
1972	22260
1973	21800
1974	21470
1975	21360
1976	21470
1977	21790
1978	22230
1979	22530
1980	22670
1981	22400
1982	21930
1983	21260
1984	20580
1985	19960
1986	19630
1987	19420
1988	19200
1989	18930
1990	18470
1991	17850
1992	17150
1993	16220
1994	15220
1995	14180
1996	13090
1997	12020
1998	11120
1999	10300
2000	9652
2001	9162
2002	8758
2003	8362
2004	8019
2005	7719
2006	7378
2007	7085
2008	6731
2009	6459
2010	6157
2011	5942
2012	5750
2013	5498
2014	5349
2015	5104