Year	Number
1960	-1990
1961	978
1962	637
1963	744
1964	-1909
1965	-1976
1966	-1247
1967	1846
1968	1647
1969	2276
1970	-1319
1971	3107
1972	5664
1973	3396
1974	4285
1975	3311
1976	4776
1977	4655
1978	3881
1979	2820
1980	3745
1981	5878
1982	5756
1983	4041
1984	3801
1985	6558
1986	7476
1987	13732
1988	10240
1989	-1739
1990	1895
1991	8076
1992	10216
1993	12589
1994	7652
1995	6522
1996	5756
1997	9777
1998	13331
1999	19147
2000	9789
2001	7888
2002	17269
2003	11447
2004	13425
2005	18467
2006	24017
2007	39806
2008	43884
2009	39234
2010	42906
2011	47281
2012	47786
2013	40480
2014	38565
2015	30329
2016	26425
2017	21584
2018	18388
2019	25564
2020	10756
2021	10604
2022	27998
2023	27998