Year	Number
1960	3108
1961	1476
1962	1384
1963	1642
1964	1563
1965	699
1966	928
1967	2108
1968	2622
1969	2896
1970	2869
1971	3596
1972	3861
1973	3327
1974	4224
1975	3680
1976	3496
1977	3926
1978	3447
1979	3323
1980	4266
1981	2549
1982	969
1983	1963
1984	1720
1985	1375
1986	1324
1987	1786
1988	1454
1989	1851
1990	1718
1991	-9
1992	-5
1993	-211
1994	-708
1995	-763
1996	-904
1997	-821
1998	-1031
1999	-1206
2000	-1562
2001	-1434
2002	5397
2003	8388
2004	8061
2005	8289
2006	8036
2007	7993
2008	7583
2009	7660
2010	7640
2011	390
2012	219
2013	210
2014	-225
2015	7934
2016	7684
2017	7460
2018	7559
2019	7427
2020	7681
2021	4568
2022	2000
2023	2000