Year	Number
1960	2646
1961	2888
1962	3171
1963	3481
1964	3811
1965	4161
1966	4531
1967	4930
1968	5354
1969	5795
1970	6260
1971	6736
1972	7226
1973	7750
1974	8312
1975	8906
1976	9523
1977	10172
1978	10850
1979	11542
1980	12243
1981	13134
1982	14418
1983	15927
1984	17474
1985	19064
1986	20703
1987	22395
1988	24139
1989	25952
1990	27845
1991	29820
1992	31345
1993	31823
1994	31735
1995	31596
1996	31410
1997	31195
1998	31240
1999	31084
2000	30519
2001	30600
2002	30777
2003	31472
2004	32488
2005	33011
2006	33441
2007	33811
2008	33964
2009	34238
2010	34056
2011	33435
2012	34640
2013	36607
2014	37685
2015	38825
2016	38992
2017	38615
2018	38934
2019	39648
2020	40350
2021	40708
2022	40888
2023	41163