Year	Number
1968	0
1969	0
1970	0
1971	0
1972	0
1973	-10
1974	-10
1975	-10
1976	-10
1977	-10
1978	-10
1979	-10
1980	-10
1981	-10
1982	-10
1983	-10
1984	-10
1985	-10
1986	-10
1987	-10
1988	-10
1989	-10
1990	-10
1991	-10
1992	-10
1993	-9
1994	-9
1995	-9
1996	-9
1997	-9
1998	-9
1999	-9
2000	-9
2001	-9
2002	-9
2003	-9
2004	-9
2005	-9
2006	-9
2007	-9
2008	-9
2009	-9
2010	-9
2011	-9