Year	Number
1855	4
1856	4
1857	4
1858	4
1859	4
1860	4
1861	4
1862	4
1863	4
1864	4
1865	4
1866	4
1867	4
1868	4
1869	4
1870	4
1871	4
1872	4
1873	4
1874	4
1875	4
1876	4
1877	4
1878	4
1879	4
1880	4
1881	4
1882	4
1883	4
1884	4
1885	4
1886	4
1887	4
1888	4
1889	4
1890	4
1891	4
1892	4
1893	4
1894	4
1895	4
1896	4
1897	4
1898	4
1899	4
1900	4
1901	4
1902	4
1903	4
1904	4
1905	4
1906	4
1907	4
1908	4
1909	4
1910	4
1911	4
1912	4
1913	4
1914	4
1915	4
1916	4
1917	4
1918	4
1919	4
1920	4
1921	4
1922	4
1923	4
1924	4
1925	4
1926	4
1927	4
1928	4
1929	4
1930	-5
1931	-5
1932	-5
1933	-5
1934	-5
1935	-5
1936	-10
1937	-10
1938	-10
1939	-10
1940	-10
1941	-10
1942	-5
1943	-5
1944	-5
1945	-5
1946	-9
1947	-9
1948	-9
1949	-9
1950	-9
1951	-9
1952	-9
1953	-9
1954	-9
1955	-9
1956	-9
1957	-9
1958	-9
1959	-9
1960	-9
1961	-9
1962	-9
1963	-9
1964	-9
1965	-9
1966	-9
1967	-9
1968	-9
1969	-9
1970	-9
1971	-9
1972	-9
1973	-9
1974	0
1975	-7
1976	-7
1977	-7
1978	-7
1979	-7
1980	-7
1981	-7
1982	-7
1983	-7
1984	-8
1985	-8
1986	-8
1987	-8
1988	-8
1989	-8
1990	-8
1991	0
1992	0
1993	0.5
1994	1
1995	1
1996	1
1997	1
1998	1
1999	1
2000	1
2001	1
2002	1
2003	1
2004	1
2005	1
2006	1
2007	1
2008	1
2009	1
2010	1
2011	1