# year    value 
 1900 4.610837 
 1901 4.080465 
 1902 4.137818 
 1903 3.925293 
 1904 3.916185 
 1905 3.979778 
 1906 4.123713 
 1907 4.104086 
 1908 4.155117 
 1909 4.178035 
 1910 4.202032 
 1911 4.143252 
 1912 4.149513 
 1913 4.143378 
 1914 4.216142 
 1915 4.147432 
 1916 4.165504 
 1917 4.264255 
 1918 4.301899 
 1919 4.227883 
 1920 4.214368 
 1921 4.207355 
 1922  4.16305 
 1923 4.242776 
 1924 4.260789 
 1925 4.244845 
 1926    4.293 
 1927 4.205736 
 1928 4.271993 
 1929  4.26401 
 1930 4.286307 
 1931 4.243802 
 1932 4.285735 
 1933 4.236292 
 1934 4.285007 
 1935  4.26514 
 1936 4.220753 
 1937  4.31755 
 1938 4.285868 
 1939 4.381553 
 1940 4.385075 
 1941 4.329364 
 1942 4.336068 
 1943 4.269892 
 1944 4.344215 
 1945 4.302153 
 1946 4.290381 
 1947 4.330092 
 1948 4.350518 
 1949 4.374491 
 1950 4.359968 
 1951 4.379311 
 1952 4.311845 
 1953 4.374586 
 1954 4.398651 
 1955  4.35363 
 1956 4.367754 
 1957 4.409642 
 1958 4.425595 
 1959 4.364469 
 1960 4.389398 
 1961 4.409038 
 1962 4.385115 
 1963 4.318656 
 1964 4.096879 
 1965 4.168742 
 1966 4.229945 
 1967 4.282202 
 1968 4.308502 
 1969 4.309772 
 1970 4.325406 
 1971 4.403209 
 1972 4.459204 
 1973 4.419856 
 1974 4.419197 
 1975 4.420731 
 1976 4.435903 
 1977  4.48877 
 1978 4.465557 
 1979 4.570164 
 1980 4.467777 
 1981 4.605782 
 1982 4.594661 
 1983 4.379244 
 1984 4.432254 
 1985  4.56495 
 1986 4.484282 
 1987 4.463063 
 1988 4.564926 
 1989 4.570557 
 1990 4.616818 
 1991 4.633049 
 1992 4.394228 
 1993 4.417674 
 1994 4.554399 
 1995 4.605419 
 1996 4.618252 
 1997 4.716206 
 1998 4.745372 
 1999 4.775913 
 2000 4.793935 
 2001 4.857049 
 2002 4.873561 
 2003 4.908348 
 2004  4.84539 
 2005 4.956425