Year	Number
1960	13949
1961	18358
1962	21222
1963	21962
1964	22282
1965	22875
1966	21867
1967	22157
1968	20914
1969	16863
1970	11294
1971	2642
1972	-1174
1973	-3372
1974	-5819
1975	-7649
1976	-10509
1977	-6731
1978	-7004
1979	-6684
1980	-5090
1981	-6734
1982	-6398
1983	-5529
1984	-28355
1985	-32108
1986	-34777
1987	-33416
1988	-32782
1989	-44108
1990	-37094
1991	-35023
1992	-65295
1993	-103695
1994	-22162
1995	-17460
1996	-9253
1997	-3550
1998	-2405
1999	-7985
2000	-21139
2001	-24266
2002	-25320
2003	-15369
2004	-17310
2005	-27130
2006	-30824
2007	-50440
2008	-37801
2009	-29651
2010	-52547
2011	-46841
2012	-41524
2013	-37188
2014	-32933
2015	-29468
2016	-25279
2017	-27796
2018	-30717
2019	-34270
2020	-14307
2021	-16510
2022	-9999
2023	-9999