Year	Number
1960	-29946
1961	-29415
1962	-28937
1963	-28761
1964	-29071
1965	-29615
1966	-30068
1967	-30149
1968	-29422
1969	-27308
1970	-24366
1971	-21320
1972	-18932
1973	-17830
1974	-17774
1975	-18344
1976	-19088
1977	-19629
1978	-19471
1979	-18142
1980	-16273
1981	-14619
1982	-13950
1983	-15060
1984	-18216
1985	-22369
1986	-26338
1987	-28956
1988	-29249
1989	-28052
1990	-26080
1991	-24007
1992	-22430
1993	-21726
1994	-20957
1995	-20084
1996	-19290
1997	-18758
1998	-18619
1999	-18545
2000	-18500
2001	-18461
2002	-18427
2003	-18382
2004	-18261
2005	-18072
2006	-17846
2007	-17588
2008	-17188
2009	-15946
2010	-14244
2011	-12578
2012	-11494
2013	-11329
2014	-11329
2015	-11329
2016	-11329
2017	-11329
2018	-11329
2019	-11329
2020	0
2021	-5664
2022	-10999
2023	-10999