# year    value 
 1901   25.263 
 1902 25.30709 
 1903 25.35282 
 1904 24.77739 
 1905 25.07372 
 1906 25.48397 
 1907 25.00608 
 1908 25.14229 
 1909  25.1156 
 1910 25.01436 
 1911 24.96784 
 1912 25.61299 
 1913 25.08727 
 1914 25.31673 
 1915 25.43376 
 1916 25.22326 
 1917 24.69756 
 1918 24.62538 
 1919 25.26712 
 1920  25.2231 
 1921 25.01126 
 1922 25.26953 
 1923 25.22232 
 1924 25.24808 
 1925 24.88436 
 1926 25.68368 
 1927 25.20965 
 1928 25.28837 
 1929 25.31985 
 1930 25.10533 
 1931 25.41962 
 1932 25.34288 
 1933  25.2362 
 1934 24.94562 
 1935  25.1663 
 1936 25.30574 
 1937 25.28805 
 1938 25.24088 
 1939 25.35532 
 1940 25.17779 
 1941 25.45353 
 1942 25.61659 
 1943 25.15438 
 1944 25.29058 
 1945 25.43847 
 1946 25.29386 
 1947  25.5381 
 1948 25.16071 
 1949 25.19697 
 1950 25.11738 
 1951 24.81867 
 1952 25.40538 
 1953 25.15092 
 1954  25.2104 
 1955 25.13184 
 1956 24.82634 
 1957 24.96046 
 1958 25.61977 
 1959 25.31755 
 1960 25.22417 
 1961 25.25524 
 1962 25.20413 
 1963 25.15046 
 1964 25.44687 
 1965 25.12237 
 1966 25.38511 
 1967 25.17486 
 1968 25.17065 
 1969 25.53061 
 1970 25.48709 
 1971 25.15239 
 1972 24.99444 
 1973 25.89246 
 1974 24.68574 
 1975 24.82226 
 1976 24.62674 
 1977 25.35718 
 1978  25.3243 
 1979 25.16548 
 1980 25.45664 
 1981 25.27858 
 1982 25.42209 
 1983 25.89892 
 1984 25.27945 
 1985 25.38446 
 1986 25.40158 
 1987 25.56322 
 1988 25.78475 
 1989 25.21608 
 1990 25.41362 
 1991 25.57089 
 1992 25.55029 
 1993 25.28675 
 1994 25.46335 
 1995 25.66836 
 1996 25.46212 
 1997 25.40384 
 1998  26.1403 
 1999 25.55401 
 2000 25.25414 
 2001 25.46598 
 2002 25.42251 
 2003 25.93294 
 2004 25.79997 
 2005 25.95595 
 2006  25.7484 
 2007 25.74495 
 2008  25.3976 
 2009 25.58195 
 2010 25.99295 
 2011 25.42224 
 2012 25.42321 
 2013  25.9038 
 2014 25.69052 
 2015 25.79218 
 2016 26.28498 
 2017 25.92171 
 2018  25.7596