Year	Number
1960	-2269
1961	55
1962	900
1963	944
1964	1004
1965	1094
1966	1230
1967	1374
1968	1520
1969	1605
1970	173
1971	-4087
1972	-6314
1973	-6412
1974	-6510
1975	-6509
1976	-7073
1977	-7431
1978	-7570
1979	-7653
1980	-5983
1981	-5679
1982	-5634
1983	-5839
1984	-6035
1985	-6193
1986	-6316
1987	-6416
1988	-6466
1989	-5701
1990	-3499
1991	-2292
1992	-1443
1993	-1203
1994	-1109
1995	-1068
1996	-1061
1997	-1068
1998	-1103
1999	-1261
2000	-2722
2001	-3110
2002	-3372
2003	-3571
2004	-3662
2005	-3673
2006	-3456
2007	-3443
2008	-3295
2009	-3429
2010	-1914
2011	-1744
2012	-1625
2013	-1585
2014	-1534
2015	-1474
2016	-1408
2017	-1354
2018	-1323
2019	-1296
2020	-1274
2021	-1274
2022	-1256
2023	-1227