Year	Number
1960	28225
1961	28143
1962	28049
1963	28002
1964	28031
1965	28043
1966	28109
1967	28140
1968	28050
1969	27964
1970	27827
1971	27666
1972	27486
1973	27283
1974	27104
1975	26904
1976	29233
1977	26291
1978	26000
1979	25704
1980	25438
1981	25128
1982	27428
1983	24155
1984	23511
1985	22761
1986	22232
1987	21886
1988	21634
1989	21324
1990	20858
1991	20339
1992	19917
1993	19547
1994	19170
1995	18787
1996	18329
1997	17847
1998	17416
1999	16911
2000	16428
2001	16054
2002	15553
2003	14936
2004	14337
2005	13740
2006	13164
2007	12705
2008	12244
2009	11781
2010	11400
2011	11048
2012	10722
2013	10359
2014	10019
2015	9747
2016	9497
2017	9154
2018	8717
2019	8229
2020	7712
2021	7272
2022	6979