Year	Number
1971	-10
1972	-10
1973	-7
1974	-7
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	-8
2002	-7
2003	-7
2004	-7
2005	-7
2006	-7
2007	-7
2008	-7
2009	-7
2010	-5
2011	-8