Year	Number
1960	8
1961	8
1962	8
1963	8
1964	7
1965	7
1966	-7
1967	-7
1968	-7
1969	-7
1970	-7
1971	-7
1972	-7
1973	-7
1974	-7
1975	-7
1976	-7
1977	-7
1978	0
1979	7
1980	7
1981	7
1982	7
1983	7
1984	-7
1985	-7
1986	-7
1987	-7
1988	-7
1989	-5
1990	-5
1991	-5
1992	-5
1993	-7
1994	-7
1995	-6
1996	-6
1997	-6
1998	-1
1999	4
2000	4
2001	4
2002	4
2003	4
2004	4
2005	4
2006	4
2007	4
2008	4
2009	4
2010	4
2011	4