Year	Number
1960	222
1961	392
1962	537
1963	639
1964	747
1965	850
1966	931
1967	984
1968	572
1969	-2237
1970	-6499
1971	-10760
1972	-13576
1973	-13875
1974	-12983
1975	-11398
1976	-9377
1977	-7131
1978	-4553
1979	-235
1980	4903
1981	9605
1982	12568
1983	12767
1984	11220
1985	8819
1986	6320
1987	4472
1988	3778
1989	3538
1990	3506
1991	3636
1992	3865
1993	4175
1994	4666
1995	5300
1996	6001
1997	6690
1998	7300
1999	7844
2000	15352
2001	15084
2002	14757
2003	14544
2004	14733
2005	15549
2006	16885
2007	18437
2008	19930
2009	21233
2010	22033
2011	17606
2012	17859
2013	18105
2014	18051
2015	17694
2016	17109
2017	16395
2018	15583
2019	14695
2020	0
2021	6486
2022	4000
2023	4000