Year	Number
1960	9338
1961	9545
1962	9810
1963	10371
1964	11888
1965	13910
1966	15854
1967	17110
1968	17260
1969	16882
1970	16164
1971	15133
1972	13851
1973	11382
1974	3347
1975	-7870
1976	-18745
1977	-35820
1978	-36651
1979	-35122
1980	-32711
1981	-30044
1982	-27752
1983	-26291
1984	-24926
1985	-18686
1986	-12693
1987	-12114
1988	-12070
1989	-12391
1990	-12986
1991	-13810
1992	-14820
1993	-16672
1994	-22681
1995	-31064
1996	-39240
1997	-44599
1998	-45291
1999	-44377
2000	-42952
2001	-41509
2002	-40555
2003	-40489
2004	-41027
2005	-41857
2006	-42731
2007	-43365
2008	-43583
2009	-43643
2010	-43569
2011	-43352
2012	-42976
2013	-45857
2014	-37405
2015	-31006
2016	-24720
2017	-20576
2018	-19973
2019	-19973
2020	-10090
2021	-10091
2022	-19999
2023	-19999