Year	Number
1960	14784
1961	15277
1962	15658
1963	12715
1964	1807
1965	-14590
1966	-20513
1967	-19626
1968	-18378
1969	-16836
1970	-15185
1971	-14218
1972	-7183
1973	17146
1974	34131
1975	43437
1976	45512
1977	47725
1978	50014
1979	52320
1980	54588
1981	56719
1982	58493
1983	59955
1984	18046
1985	11961
1986	5843
1987	1742
1988	1052
1989	984
1990	947
1991	904
1992	843
1993	426
1994	-1762
1995	-5066
1996	-8448
1997	-10908
1998	-11479
1999	-10203
2000	31970
2001	31097
2002	35582
2003	39618
2004	42112
2005	41035
2006	3351
2007	12641
2008	15257
2009	11670
2010	9613
2011	-862825
2012	5211
2013	25760
2014	-1712
2015	-7660
2016	-5081
2017	9208
2018	5835
2019	-1352
2020	-696
2021	-696
2022	-2000
2023	-2000