Year	Number
1960	16242
1961	16324
1962	16346
1963	16361
1964	16358
1965	16375
1966	16406
1967	16481
1968	16644
1969	16901
1970	17259
1971	17694
1972	18221
1973	18899
1974	19638
1975	20365
1976	21049
1977	21616
1978	22005
1979	21972
1980	21824
1981	22447
1982	22740
1983	22049
1984	21033
1985	19924
1986	19046
1987	18478
1988	18064
1989	17827
1990	17935
1991	18325
1992	18825
1993	19224
1994	19434
1995	19783
1996	20150
1997	20573
1998	20873
1999	21086
2000	21293
2001	21485
2002	21647
2003	21762
2004	22252
2005	22563
2006	23258
2007	23911
2008	24388
2009	24893
2010	24625
2011	24446
2012	22663
2013	21902
2014	20924
2015	20178
2016	19274
2017	18727
2018	18129
2019	17772
2020	17561
2021	17182
2022	16872