# year    value 
 1901  26.0832 
 1902 26.26487 
 1903 26.15023 
 1904  25.9295 
 1905 26.23679 
 1906 26.24329 
 1907 25.89683 
 1908 26.08775 
 1909  25.8951 
 1910 26.01175 
 1911 26.04374 
 1912 26.17508 
 1913 25.85472 
 1914 26.24413 
 1915 26.45161 
 1916 26.00625 
 1917 25.96247 
 1918 26.05482 
 1919 26.19324 
 1920 25.98631 
 1921 26.10755 
 1922 26.22077 
 1923 26.38707 
 1924 26.47345 
 1925 26.11617 
 1926 26.45982 
 1927 26.44861 
 1928 26.18534 
 1929 26.12005 
 1930 26.29375 
 1931 26.37829 
 1932 26.23233 
 1933 26.22005 
 1934 26.06721 
 1935 26.28781 
 1936 25.94347 
 1937 26.25126 
 1938 26.00733 
 1939 26.61749 
 1940 26.24971 
 1941 26.65633 
 1942 26.46483 
 1943 26.26669 
 1944 26.64003 
 1945 26.54929 
 1946 26.31186 
 1947 26.30396 
 1948 26.56662 
 1949 26.13185 
 1950 26.22189 
 1951 26.36221 
 1952 26.32139 
 1953 26.62673 
 1954 26.01045 
 1955 26.45609 
 1956 25.85345 
 1957 25.98801 
 1958  26.3911 
 1959   26.175 
 1960 26.32133 
 1961 26.35178 
 1962 26.34839 
 1963 26.30288 
 1964 26.04261 
 1965 26.20745 
 1966 26.46358 
 1967 26.25625 
 1968 26.17289 
 1969 25.98322 
 1970  26.1591 
 1971 25.92168 
 1972 26.11064 
 1973 26.25498 
 1974 26.20526 
 1975 26.32147 
 1976 25.76349 
 1977 26.35573 
 1978 26.29612 
 1979 26.38759 
 1980 26.30536 
 1981 26.47634 
 1982 26.23429 
 1983 26.50029 
 1984 26.35402 
 1985 26.24683 
 1986 26.21869 
 1987 26.43023 
 1988  26.6225 
 1989 26.16395 
 1990 26.36237 
 1991 26.58402 
 1992 26.10855 
 1993 26.02187 
 1994 26.57471 
 1995 26.79344 
 1996 26.24941 
 1997 26.70114 
 1998 26.95123 
 1999 26.66232 
 2000 26.85499 
 2001 26.66182 
 2002 26.96136 
 2003 26.48866 
 2004 26.60784 
 2005 27.13218 
 2006 26.92787 
 2007 27.09383 
 2008 26.83512 
 2009  26.9435 
 2010 27.23622 
 2011 27.03136 
 2012 27.05503 
 2013 26.79292 
 2014 26.94341 
 2015 26.90604 
 2016 27.23746 
 2017 27.20117 
 2018 27.25318