Year	Number of
1960	15650
1961	15970
1962	15960
1963	15450
1964	14850
1965	14240
1966	13640
1967	12830
1968	11960
1969	11180
1970	10610
1971	9992
1972	9415
1973	8735
1974	8199
1975	7655
1976	7109
1977	6558
1978	5942
1979	5466
1980	5049
1981	4821
1982	4697
1983	4571
1984	4481
1985	4336
1986	4202
1987	3946
1988	3745
1989	3543
1990	3432
1991	3339
1992	3332
1993	3252
1994	3165
1995	3063
1996	2944
1997	2816
1998	2760
1999	2639
2000	2601
2001	2503
2002	2415
2003	2415
2004	2383
2005	2459
2006	2510
2007	2592
2008	2672
2009	2706
2010	2670
2011	2557
2012	2388
2013	2196
2014	1946
2015	1820