Year	Number
1960	14392
1961	14505
1962	14722
1963	15050
1964	15415
1965	15773
1966	16120
1967	16473
1968	16843
1969	17208
1970	17518
1971	17700
1972	17798
1973	17911
1974	18034
1975	18174
1976	18324
1977	18444
1978	18555
1979	18682
1980	18813
1981	18930
1982	18956
1983	18879
1984	18776
1985	18673
1986	18573
1987	18468
1988	18350
1989	18242
1990	18139
1991	18043
1992	18032
1993	18065
1994	18078
1995	18103
1996	18139
1997	18179
1998	18198
1999	18213
2000	18244
2001	18287
2002	18434
2003	18671
2004	18908
2005	19162
2006	19487
2007	19875
2008	20238
2009	20536
2010	20716
2011	20861
2012	21086
2013	21167
2014	21057
2015	20942
2016	20824
2017	20716
2018	20636
2019	20573
2020	20517
2021	20407
2022	20284
2023	20201