Year	Number of
1951	32430
1952	29020
1953	26250
1954	24170
1955	22470
1956	21030
1957	19960
1958	19210
1959	18770
1960	18520
1961	18830
1962	19240
1963	19640
1964	19890
1965	20070
1966	20140
1967	19940
1968	19520
1969	18880
1970	17930
1971	16760
1972	15490
1973	14110
1974	12250
1975	10220
1976	8408
1977	6860
1978	5651
1979	4758
1980	4111
1981	3835
1982	3648
1983	3536
1984	3420
1985	3185
1986	2742
1987	2385
1988	1961
1989	1682
1990	1514
1991	1470
1992	1555
1993	1584
1994	1631
1995	1517
1996	1392
1997	1288
1998	1215
1999	1191
2000	1235
2001	1320
2002	1399
2003	1419
2004	1350
2005	1270
2006	1122
2007	1021
2008	966
2009	910
2010	851
2011	839
2012	824
2013	806
2014	791
2015	733