Year	Number
1948	7
1949	7
1950	7
1951	7
1952	7
1953	7
1954	7
1955	7
1956	7
1957	7
1958	7
1959	7
1960	7
1961	7
1962	7
1963	7
1964	7
1965	7
1966	7
1967	7
1968	7
1969	7
1970	8
1971	8
1972	8
1973	8
1974	8
1975	8
1976	8
1977	8
1978	6
1979	6
1980	6
1981	6
1982	5
1983	5
1984	5
1985	5
1986	5
1987	5
1988	5
1989	5
1990	5
1991	5
1992	5
1993	5
1994	5
1995	5
1996	5
1997	5
1998	5
1999	5
2000	5
2001	6
2002	6
2003	5
2004	5
2005	5
2006	6
2007	6
2008	6
2009	6
2010	4
2011	4