# year    value 
 1900 7.897017 
 1901 8.061636 
 1902 7.904597 
 1903 7.365991 
 1904 7.515462 
 1905 7.949592 
 1906 7.907875 
 1907 7.946612 
 1908  7.72182 
 1909  7.85606 
 1910 7.741043 
 1911 7.782427 
 1912 7.495492 
 1913 7.830708 
 1914 7.701779 
 1915 7.932163 
 1916 7.934088 
 1917 7.924367 
 1918 7.997287 
 1919 8.268284 
 1920 7.935537 
 1921 7.914571 
 1922 7.920576 
 1923 8.058255 
 1924 7.901201 
 1925 8.042776 
 1926 7.967301 
 1927 8.105976 
 1928 8.014221 
 1929 7.921866 
 1930 7.910341 
 1931 8.121104 
 1932 7.855924 
 1933 8.131913 
 1934 8.092566 
 1935 8.102643 
 1936 8.019375 
 1937 8.124932 
 1938 8.124958 
 1939 7.885451 
 1940 8.256452 
 1941 8.199116 
 1942 7.958487 
 1943 8.095497 
 1944 8.063482 
 1945 7.974854 
 1946  8.11974 
 1947 7.865356 
 1948 8.023429 
 1949 8.202722 
 1950  8.33812 
 1951 8.097486 
 1952 8.088018 
 1953 8.014193 
 1954  8.09314 
 1955 7.998714 
 1956 7.968188 
 1957 7.927309 
 1958 8.125974 
 1959 8.013929 
 1960 8.046529 
 1961 7.921014 
 1962 7.940512 
 1963  7.76689 
 1964 7.655098 
 1965 7.766849 
 1966 7.860255 
 1967  7.89542 
 1968 7.790493 
 1969 7.597537 
 1970 7.766376 
 1971 7.648363 
 1972  7.90869 
 1973 7.890144 
 1974 8.038801 
 1975 7.808324 
 1976 7.733487 
 1977 8.053976 
 1978 8.135503 
 1979 8.117437 
 1980 8.164292 
 1981 8.325552 
 1982 8.147669 
 1983 7.779236 
 1984 8.167718 
 1985 8.131692 
 1986 8.310541 
 1987 8.286339 
 1988 8.384054 
 1989  8.51946 
 1990 8.339014 
 1991 8.166362 
 1992 8.034321 
 1993 8.101988 
 1994 8.486542 
 1995 8.511197 
 1996 8.726444 
 1997 8.746158 
 1998 8.872488 
 1999 8.703444 
 2000 9.020616 
 2001 9.226557 
 2002 8.813148 
 2003 9.112888 
 2004 9.010097 
 2005 9.069147