Year	Number
1960	9976
1961	10290
1962	10604
1963	10903
1964	11186
1965	11469
1966	11721
1967	11928
1968	12115
1969	12311
1970	12525
1971	12735
1972	12931
1973	13072
1974	13020
1975	12797
1976	12558
1977	12323
1978	12095
1979	12005
1980	12052
1981	12109
1982	12197
1983	12328
1984	12515
1985	12779
1986	13130
1987	13546
1988	13994
1989	14457
1990	14917
1991	15335
1992	15700
1993	16023
1994	16294
1995	16532
1996	16777
1997	17011
1998	17214
1999	17382
2000	17521
2001	17731
2002	17967
2003	18139
2004	18322
2005	18560
2006	18739
2007	18837
2008	18970
2009	19123
2010	19257
2011	19429
2012	19654
2013	19884
2014	20135
2015	20426
2016	20768
2017	21163
2018	21599
2019	22036
2020	22449
2021	22826
2022	23139
2023	23382