Year	Ratio
1878	410
1883	400
1888	360
1893	300
1898	250
1903	240
1905	240
1906	250
1907	230
1908	250
1909	220
1910	250
1911	240
1912	240
1913	210
1914	210
1915	250
1916	260
1917	250
1918	300
1919	340
1920	240
1921	231
1922	249
1923	232
1924	239
1925	264
1926	285
1927	290
1928	334
1929	333
1930	333
1931	320
1932	300
1933	317
1934	318
1935	293
1936	302
1937	257
1938	268
1939	247
1940	235
1941	192
1942	195
1943	195
1944	229
1945	194
1946	149
1947	140
1948	122
1949	109
1950	105
1951	85.3
1952	75.9
1953	78.2
1954	69.8
1955	61
1956	66
1957	61.3
1958	42.5
1959	51.3
1960	38.4
1961	37.7
1962	33.6
1963	33.5
1964	33.8
1965	25.1
1966	20.8
1967	26.4
1968	21.5
1969	20.8
1970	15.8
1971	12.4
1972	11.4
1973	11.7
1974	11.6
1975	9.9
1976	9.5
1977	9.5
1978	10.1
1979	10.1
1980	9.5
1990	11
1995	11
2000	15
2005	10
2010	7
2013	6