Year	Number
1960	15931
1961	16076
1962	16244
1963	16364
1964	16446
1965	16478
1966	16443
1967	16365
1968	16227
1969	16025
1970	15823
1971	15732
1972	15680
1973	15553
1974	15370
1975	15139
1976	14851
1977	14528
1978	14148
1979	13738
1980	14703
1981	12822
1982	12200
1983	11513
1984	10890
1985	10277
1986	9719
1987	9344
1988	9038
1989	8659
1990	8248
1991	7853
1992	7469
1993	7085
1994	6715
1995	6345
1996	5956
1997	5566
1998	5242
1999	4926
2000	4548
2001	4144
2002	3731
2003	3362
2004	3041
2005	2765
2006	2547
2007	2359
2008	2197
2009	2067
2010	1958
2011	1865
2012	1772
2013	1684
2014	1609
2015	1529
2016	1425
2017	1323
2018	1238
2019	1176
2020	1124
2021	1075
2022	1028