Year	Number
1960	1586
1961	3177
1962	3771
1963	4278
1964	4684
1965	5082
1966	5880
1967	6637
1968	7270
1969	7790
1970	10398
1971	10404
1972	10381
1973	10298
1974	10201
1975	10070
1976	9953
1977	9803
1978	9711
1979	9670
1980	9672
1981	9667
1982	9580
1983	9319
1984	8941
1985	8632
1986	6348
1987	5396
1988	5049
1989	4904
1990	5021
1991	5494
1992	5451
1993	5250
1994	5106
1995	4893
1996	4552
1997	19387
1998	22500
1999	22364
2000	22039
2001	21641
2002	24200
2003	23444
2004	12430
2005	106609
2006	203572
2007	206156
2008	192654
2009	111510
2010	64531
2011	82815
2012	83444
2013	137597
2014	179768
2015	178133
2016	138455
2017	46900
2018	11662
2019	15493
2020	-163999
2021	-30801
2022	0
2023	0