Year	Number
1961	6
1962	6
1963	6
1964	6
1965	6
1966	6
1967	-7
1968	1
1969	1
1970	1
1971	-6
1972	-6
1973	-6
1974	-6
1975	-6
1976	-6
1977	-6
1978	-7
1979	-7
1980	-7
1981	-7
1982	-7
1983	-7
1984	-7
1985	-7
1986	-7
1987	-7
1988	-7
1989	-7
1990	-7
1991	-6
1992	-7
1993	-7
1994	-7
1995	-7
1996	4
1997	0
1998	0
1999	0
2000	0
2001	2
2002	5
2003	5
2004	5
2005	5
2006	5
2007	7
2008	7
2009	7
2010	7
2011	7