Year	Number
1960	4
1961	4
1962	4
1963	-7
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	-7
1979	-8
1980	-8
1981	-8
1982	-8
1983	-8
1984	-8
1985	-8
1986	-8
1987	-8
1988	-8
1989	-8
1990	-8
1991	-1
1992	5
1993	5
1994	5
1995	5
1996	5
1997	-6
1998	-6
1999	-6
2000	-6
2001	-5
2002	-4
2003	-4
2004	-4
2005	-4
2006	-4
2007	-4
2008	-4
2009	-4
2010	-4
2011	-4