Year	Number
1960	2591
1961	2772
1962	2966
1963	3170
1964	3367
1965	4055
1966	5459
1967	9797
1968	10287
1969	10316
1970	10278
1971	10211
1972	10172
1973	10202
1974	10300
1975	8959
1976	5641
1977	1123
1978	947
1979	960
1980	950
1981	960
1982	967
1983	1016
1984	1065
1985	398
1986	-1321
1987	-9727
1988	-11357
1989	-12087
1990	-12891
1991	-13676
1992	-14381
1993	-15018
1994	-15511
1995	-16279
1996	-17727
1997	-20220
1998	-21347
1999	-22483
2000	-23572
2001	-24606
2002	-25582
2003	-26420
2004	-27129
2005	-22692
2006	-11085
2007	-9748
2008	-3102
2009	-4626
2010	-6204
2011	-6852
2012	-6827
2013	-6452
2014	-5466
2015	-4129
2016	-3861
2017	-3327
2018	-3234
2019	-2989
2020	-1490
2021	-1490
2022	-4000
2023	-4000