Year	Number
1959	7
1960	7
1961	7
1962	7
1963	4
1964	1
1965	-2
1966	-2
1967	-2
1968	-2
1969	-2
1970	-2
1971	-2
1972	-2
1973	-2
1974	-2
1975	-2
1976	-2
1977	-2
1978	-2
1979	-2
1980	-2
1981	-2
1982	-2
1983	-2
1984	-2
1985	-2
1986	-2
1987	-2
1988	-2
1989	-2
1990	-2
1991	-2
1992	-2
1993	-2
1994	-2
1995	-2
1996	-2
1997	-2
1998	-2
1999	-2
2000	-2
2001	-2
2002	-2
2003	-2
2004	-2
2005	-2
2006	-2
2007	-2
2008	-2
2009	-2
2010	-2
2011	-2