Year	Number
1918	-10
1919	-10
1920	-10
1921	-10
1922	-10
1923	-10
1924	-10
1925	-10
1926	-10
1927	-10
1928	-10
1929	-10
1930	-10
1931	-10
1932	-10
1933	-10
1934	-10
1935	-10
1936	-10
1937	-10
1938	-10
1939	-10
1940	-10
1941	-10
1942	-10
1943	-10
1944	-10
1945	-10
1946	-9
1947	-7
1948	-6
1949	-6
1950	-6
1951	-6
1952	-6
1953	-6
1954	-6
1955	-6
1956	-6
1957	-6
1958	-6
1959	-6
1960	-6
1961	-6
1962	0
1963	0
1964	0
1965	0
1966	-3
1967	-3
1968	-3
1969	-3
1970	-3
1971	-3
1972	-3
1973	-3
1974	-4
1975	-4
1976	-4
1977	-6
1978	-6
1979	-6
1980	-6
1981	-6
1982	-6
1983	-6
1984	-6
1985	-6
1986	-6
1987	-6
1988	-5
1989	-5
1990	-5