Year	Number
1960	17397
1961	17879
1962	18361
1963	18851
1964	19373
1965	19916
1966	20469
1967	20914
1968	21232
1969	21543
1970	21882
1971	22248
1972	22647
1973	23080
1974	23541
1975	24016
1976	24488
1977	24892
1978	25195
1979	25437
1980	25636
1981	25800
1982	25946
1983	26077
1984	26180
1985	26240
1986	26256
1987	26433
1988	26757
1989	27008
1990	27184
1991	27299
1992	27368
1993	27422
1994	27482
1995	27545
1996	27623
1997	27884
1998	28283
1999	28633
2000	28929
2001	29167
2002	29346
2003	29478
2004	29583
2005	29681
2006	29792
2007	29928
2008	30064
2009	30162
2010	30233
2011	30229
2012	30156
2013	30067
2014	29957
2015	29843
2016	29782
2017	29786
2018	29818
2019	29862
2020	30094
2021	30532
2022	30977
2023	31387