Year	Number
1847	4
1848	4
1849	4
1850	4
1851	4
1852	4
1853	4
1854	4
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	-3
1885	-3
1886	-3
1887	-3
1888	-3
1889	-3
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	-6
1910	-6
1911	-6
1912	-6
1913	-6
1914	-6
1915	-6
1916	-6
1917	-6
1918	-6
1919	-6
1920	-6
1921	-6
1922	-6
1923	-6
1924	-6
1925	-6
1926	-6
1927	-6
1928	-6
1929	-6
1930	-6
1931	-6
1932	-6
1933	-6
1934	-6
1935	-6
1936	-6
1937	-6
1938	-6
1939	-6
1940	-6
1941	-6
1942	-6
1943	-6
1944	-6
1945	-6
1946	-6
1947	-6
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	-6
1963	-6
1964	-6
1965	-6
1966	-6
1967	-6
1968	-6
1969	-6
1970	-6
1971	-6
1972	-6
1973	-6
1974	-6
1975	-6
1976	-6
1977	-6
1978	-6
1979	-6
1980	-7
1981	-7
1982	-7
1983	-7
1984	-6
1985	-6
1986	-6
1987	-6
1988	-6
1989	-6
1990	0
1991	0
1992	0
1993	0
1994	0
1995	0
1996	0
1997	0
1998	0
1999	0
2000	0
2001	0
2002	0
2003	1
2004	3
2005	5
2006	6
2007	6
2008	6
2009	6
2010	6
2011	6