Year	Number
1960	17708
1961	17951
1962	18193
1963	18428
1964	18662
1965	18896
1966	19133
1967	19366
1968	19597
1969	19847
1970	20109
1971	20359
1972	20603
1973	20839
1974	21071
1975	21306
1976	21541
1977	21785
1978	22031
1979	22274
1980	22520
1981	22762
1982	23005
1983	23253
1984	23506
1985	23761
1986	24020
1987	24287
1988	24559
1989	24834
1990	25112
1991	25397
1992	25688
1993	25990
1994	26295
1995	26608
1996	26935
1997	27268
1998	27618
1999	27981
2000	28349
2001	28736
2002	29145
2003	29572
2004	30009
2005	30457
2006	30946
2007	31498
2008	32096
2009	32752
2010	33488
2011	34311
2012	35218
2013	36126
2014	37021
2015	37951
2016	38869
2017	39744
2018	40629
2019	41577
2020	42459
2021	43127
2022	43718
2023	44520