Year	Number
1960	19450
1961	19323
1962	19221
1963	19122
1964	19103
1965	19269
1966	19734
1967	20467
1968	21479
1969	22681
1970	23950
1971	25236
1972	26613
1973	28197
1974	29937
1975	31791
1976	33666
1977	35072
1978	35464
1979	35024
1980	34007
1981	32807
1982	31726
1983	30943
1984	30312
1985	29716
1986	29281
1987	29152
1988	29134
1989	29241
1990	29820
1991	31203
1992	33381
1993	36353
1994	68542
1995	33841
1996	30374
1997	35346
1998	38895
1999	38034
2000	35665
2001	32925
2002	30041
2003	27417
2004	25018
2005	22985
2006	21130
2007	19512
2008	18055
2009	16900
2010	15746
2011	14462
2012	13756
2013	13224
2014	12884
2015	12684
2016	12584
2017	12487
2018	12358
2019	12180
2020	11959
2021	11773
2022	11587