Year	Number
1960	23333
1961	24615
1962	25967
1963	27333
1964	28674
1965	30024
1966	31499
1967	33159
1968	34969
1969	36685
1970	37791
1971	38405
1972	38938
1973	39350
1974	39599
1975	39651
1976	39570
1977	39435
1978	39242
1979	39036
1980	38858
1981	38843
1982	38984
1983	39181
1984	39563
1985	40106
1986	40647
1987	41167
1988	41683
1989	42218
1990	42656
1991	43110
1992	43883
1993	44898
1994	45793
1995	46467
1996	47039
1997	47543
1998	47980
1999	48225
2000	48256
2001	48202
2002	48213
2003	48347
2004	48500
2005	48642
2006	48827
2007	49028
2008	49276
2009	49634
2010	49579
2011	48971
2012	48284
2013	47436
2014	46569
2015	45771
2016	44849
2017	43845
2018	42820
2019	41804
2020	40796
2021	39794
2022	38774
2023	37750