Year	Number of
1956	11870
1957	11580
1958	11230
1959	10980
1960	10900
1961	10970
1962	11180
1963	11470
1964	11750
1965	11900
1966	11910
1967	11870
1968	11790
1969	11720
1970	11580
1971	11380
1972	11170
1973	10940
1974	10690
1975	10420
1976	10090
1977	9770
1978	9507
1979	9250
1980	9028
1981	8837
1982	8651
1983	8467
1984	8282
1985	8122
1986	7951
1987	7806
1988	7677
1989	7557
1990	7378
1991	7165
1992	6929
1993	6713
1994	6497
1995	6262
1996	6081
1997	5940
1998	5796
1999	5636
2000	5451
2001	5242
2002	5014
2003	4817
2004	4640
2005	4496
2006	4420
2007	4369
2008	4325
2009	4268
2010	4181
2011	4062
2012	3920
2013	3765
2014	3644
2015	3530