Year	Number
1960	20400656
1961	20287312
1962	20171158
1963	20063620
1964	19972523
1965	19884509
1966	19781807
1967	19667348
1968	19532729
1969	19385021
1970	19229471
1971	19060905
1972	19012262
1973	19031041
1974	19045214
1975	19047865
1976	19031129
1977	19000219
1978	18956292
1979	18899110
1980	18826343
1981	18737650
1982	18723830
1983	18741940
1984	18757445
1985	18774185
1986	18786528
1987	18799765
1988	18820178
1989	18845634
1990	18872760
1991	18897182
1992	18889575
1993	18867028
1994	18836766
1995	18802959
1996	18774128
1997	18749929
1998	18721181
1999	18690180
2000	18664484
2001	18640786
2002	18611507
2003	18626218
2004	18678509
2005	18702115
2006	18689801
2007	18715453
2008	18770433
2009	18787007
2010	18774936
2011	18737779
2012	18645458
2013	18685173
2014	18679287
2015	18483353
2016	18276159
2017	18073840
2018	17861881
2019	17479118
2020	17214086
2021	16944019
2022	16705485
2023	16468986