Year	Number
1960	15374
1961	15867
1962	16387
1963	16947
1964	17537
1965	18154
1966	18794
1967	19665
1968	21001
1969	22623
1970	23969
1971	24680
1972	25084
1973	25522
1974	26174
1975	27047
1976	27964
1977	28912
1978	29892
1979	30902
1980	31988
1981	33219
1982	34569
1983	35975
1984	37437
1985	38962
1986	40527
1987	42122
1988	43687
1989	44988
1990	46047
1991	47053
1992	48015
1993	48944
1994	49840
1995	50702
1996	51538
1997	52358
1998	53164
1999	53834
2000	54224
2001	54413
2002	54496
2003	54493
2004	54435
2005	54337
2006	54208
2007	54038
2008	53816
2009	53593
2010	53416
2011	52971
2012	52203
2013	51352
2014	50419
2015	49410
2016	48329
2017	47187
2018	45989
2019	44728
2020	43413
2021	42050
2022	41569
2023	41996