Year	Number
1960	22954
1961	23249
1962	23470
1963	23688
1964	23596
1965	23306
1966	23126
1967	23108
1968	23220
1969	23280
1970	23452
1971	23722
1972	24091
1973	24702
1974	26461
1975	29344
1976	32254
1977	35115
1978	37843
1979	39030
1980	39606
1981	41014
1982	42394
1983	43746
1984	45037
1985	46250
1986	47397
1987	48486
1988	49529
1989	50540
1990	51522
1991	51471
1992	50632
1993	50099
1994	49544
1995	48792
1996	47900
1997	46934
1998	45954
1999	45036
2000	44256
2001	43607
2002	43040
2003	42535
2004	42106
2005	41761
2006	41521
2007	41421
2008	41456
2009	41646
2010	42010
2011	42568
2012	43348
2013	44352
2014	45562
2015	46990
2016	48644
2017	50481
2018	52465
2019	54560
2020	56431
2021	57944
2022	59368
2023	60997