Year	Number
1970	22300
1971	22300
1972	22300
1973	22300
1974	22300
1975	26900
1976	26900
1977	25300
1978	25300
1979	25300
1980	26600
1981	24030
1982	24971
1983	25630
1984	28670
1985	29010
1986	29000
1987	29000
1988	29186
1989	32000
1990	34000
1991	35000
1992	36000
1993	36000
1994	36000
1995	36000
1996	36000
1997	9100
1998	9350
1999	9550
2000	9810
2001	9980
2002	10000
2003	9733
2004	10524
2005	10579
2006	9700
2007	3500
2008	37320
2009	42320
2010	41990
2011	56970
2012	59534
2013	0
2014	0
2015	0
2016	0
2017	0
2018	0
2019	0
2020	0
2021	0