Year	Number
1960	16623
1961	16720
1962	16924
1963	17160
1964	17342
1965	17520
1966	17624
1967	17638
1968	17559
1969	17429
1970	17342
1971	17336
1972	17364
1973	17558
1974	17823
1975	18200
1976	18698
1977	19190
1978	19596
1979	20011
1980	20295
1981	20732
1982	20951
1983	20422
1984	20181
1985	20094
1986	20111
1987	20100
1988	20090
1989	20204
1990	20516
1991	20940
1992	21324
1993	21657
1994	21948
1995	22111
1996	22152
1997	22145
1998	22256
1999	22432
2000	22295
2001	22211
2002	22497
2003	22998
2004	23537
2005	23946
2006	24333
2007	24698
2008	25018
2009	25336
2010	25512
2011	25561
2012	25537
2013	25602
2014	25673
2015	26070
2016	26388
2017	26444
2018	26185
2019	26000
2020	25706
2021	25475
2022	25162