Year	Number
1960	21946
1961	21958
1962	21906
1963	21850
1964	21829
1965	21836
1966	21829
1967	21824
1968	21823
1969	21828
1970	21819
1971	21955
1972	21982
1973	21954
1974	21922
1975	21911
1976	21947
1977	22042
1978	22166
1979	22315
1980	22463
1981	22580
1982	22687
1983	22801
1984	22837
1985	22780
1986	22715
1987	22641
1988	22563
1989	22492
1990	22435
1991	22568
1992	22686
1993	22850
1994	23029
1995	23229
1996	23445
1997	23659
1998	23844
1999	23984
2000	24113
2001	24191
2002	24006
2003	23785
2004	23554
2005	23336
2006	23141
2007	22966
2008	22815
2009	22670
2010	22485
2011	22292
2012	22380
2013	22434
2014	22465
2015	22485
2016	22502
2017	22518
2018	22539
2019	22574
2020	22641
2021	22727
2022	22828
2023	22945