Year	Number
1960	-726
1961	-400
1962	152
1963	545
1964	1060
1965	1584
1966	2089
1967	2561
1968	2961
1969	3337
1970	3763
1971	4087
1972	4349
1973	4568
1974	4635
1975	4643
1976	4527
1977	4254
1978	3905
1979	3449
1980	2904
1981	2575
1982	2456
1983	2606
1984	2926
1985	3498
1986	4227
1987	5265
1988	6443
1989	7849
1990	9449
1991	10812
1992	11990
1993	13011
1994	13723
1995	14157
1996	14394
1997	14313
1998	13972
1999	13391
2000	12536
2001	11934
2002	11518
2003	11337
2004	11366
2005	11693
2006	12217
2007	13067
2008	14111
2009	15469
2010	17037
2011	18519
2012	19732
2013	20779
2014	21670
2015	22368
2016	22859
2017	23188
2018	23337
2019	23305
2020	23076
2021	22746
2022	19999
2023	19999