Year	Number
1960	32256
1961	27420
1962	22260
1963	18490
1964	16284
1965	15260
1966	15758
1967	23710
1968	32148
1969	29742
1970	24303
1971	20639
1972	18855
1973	17734
1974	17625
1975	17641
1976	16779
1977	15980
1978	15327
1979	14693
1980	13977
1981	12948
1982	11504
1983	10252
1984	10136
1985	10665
1986	11465
1987	12393
1988	12709
1989	12102
1990	10547
1991	8953
1992	8097
1993	7611
1994	7194
1995	6743
1996	6282
1997	5997
1998	5727
1999	5296
2000	4867
2001	4550
2002	4392
2003	4343
2004	4220
2005	4034
2006	3764
2007	3440
2008	3258
2009	3135
2010	2896
2011	2574
2012	2348
2013	2158
2014	1993
2015	1886
2016	1777
2017	1679
2018	1555
2019	1420
2020	1324
2021	1291
2022	1320