# year    value 
 1901 24.60231 
 1902 24.52276 
 1903 24.34609 
 1904 24.42672 
 1905 24.71091 
 1906 24.54009 
 1907 24.54553 
 1908 24.48903 
 1909 24.59844 
 1910 24.34847 
 1911 24.49436 
 1912 24.32606 
 1913 24.43453 
 1914 24.53052 
 1915 24.74413 
 1916 24.29062 
 1917 24.24076 
 1918 24.63205 
 1919 24.63283 
 1920 24.59609 
 1921 24.47458 
 1922 24.46286 
 1923 24.54288 
 1924 24.46925 
 1925 24.67182 
 1926  24.6853 
 1927 24.81246 
 1928 24.63782 
 1929 24.46053 
 1930 24.67471 
 1931 24.73745 
 1932 24.66396 
 1933 24.57106 
 1934 24.82231 
 1935 24.78322 
 1936 24.70487 
 1937 24.93881 
 1938 24.74235 
 1939  24.8103 
 1940 24.85031 
 1941  24.9815 
 1942 24.86011 
 1943 24.67581 
 1944 24.66819 
 1945 24.61666 
 1946 24.78618 
 1947 24.71554 
 1948 24.42235 
 1949  24.5852 
 1950 24.35727 
 1951 24.84529 
 1952 24.56961 
 1953 24.57012 
 1954 24.43329 
 1955  24.4994 
 1956 24.25981 
 1957 24.80156 
 1958 24.71259 
 1959 24.49107 
 1960 24.73946 
 1961 24.23648 
 1962 24.71811 
 1963 24.79422 
 1964 24.19438 
 1965 24.58591 
 1966 24.68399 
 1967 24.17987 
 1968 24.62831 
 1969   24.806 
 1970 24.39648 
 1971 24.11823 
 1972 24.76563 
 1973 24.51532 
 1974 24.40869 
 1975 24.25434 
 1976 24.54256 
 1977 24.60503 
 1978 24.50667 
 1979  24.9576 
 1980 24.94843 
 1981 24.69088 
 1982 24.70917 
 1983 24.89337 
 1984 24.65212 
 1985  24.7433 
 1986 24.68307 
 1987 25.23021 
 1988 24.71607 
 1989 24.94012 
 1990 25.21469 
 1991 24.75058 
 1992 24.59633 
 1993 25.08222 
 1994 24.81848 
 1995 25.05059 
 1996  24.8754 
 1997 25.29939 
 1998 25.39646 
 1999 25.04981 
 2000 24.94892 
 2001 25.23037 
 2002   25.302 
 2003 25.40796 
 2004 25.28275 
 2005 25.32389 
 2006 25.26491 
 2007 25.23415 
 2008 25.19808 
 2009 25.47645 
 2010  25.5727 
 2011 25.19326 
 2012 25.38512 
 2013 25.19095 
 2014 25.33385 
 2015 25.75333 
 2016 25.59788 
 2017 25.45636 
 2018 25.31537