# year    value 
 1901 25.79937 
 1902 25.71905 
 1903 25.55642 
 1904 25.65186 
 1905  25.9202 
 1906  25.7592 
 1907 25.76703 
 1908 25.69798 
 1909 25.78517 
 1910 25.55361 
 1911 25.71022 
 1912 25.54443 
 1913 25.65089 
 1914   25.758 
 1915 25.91533 
 1916 25.47021 
 1917 25.39026 
 1918 25.84294 
 1919 25.87447 
 1920 25.77854 
 1921 25.67516 
 1922 25.65242 
 1923 25.74484 
 1924 25.64742 
 1925 25.90034 
 1926 25.87825 
 1927 26.00375 
 1928 25.85534 
 1929 25.66451 
 1930 25.89885 
 1931 25.93752 
 1932  25.8984 
 1933 25.74089 
 1934 26.04934 
 1935 25.97588 
 1936 25.93411 
 1937 26.17043 
 1938 25.98915 
 1939 26.03238 
 1940 26.04089 
 1941 26.21583 
 1942 26.05247 
 1943 25.87386 
 1944 25.88565 
 1945 25.78201 
 1946 25.95307 
 1947 25.89332 
 1948 25.63362 
 1949 25.78662 
 1950 25.52994 
 1951   26.017 
 1952 25.74688 
 1953 25.75587 
 1954   25.597 
 1955 25.69282 
 1956 25.45592 
 1957 26.04071 
 1958 25.92242 
 1959 25.67225 
 1960 25.93142 
 1961 25.40005 
 1962 25.95392 
 1963 25.98868 
 1964 25.34483 
 1965 25.77987 
 1966 25.91979 
 1967 25.39492 
 1968 25.83305 
 1969 26.04012 
 1970 25.60401 
 1971 25.31483 
 1972 25.97044 
 1973 25.70707 
 1974 25.58094 
 1975 25.41692 
 1976  25.7888 
 1977 25.77644 
 1978  25.6936 
 1979 26.22716 
 1980 26.16531 
 1981  25.8988 
 1982 25.90331 
 1983 26.07447 
 1984 25.89611 
 1985  25.9562 
 1986 25.91906 
 1987 26.45429 
 1988 25.91493 
 1989 26.16078 
 1990 26.45045 
 1991 25.98871 
 1992 25.82291 
 1993 26.33778 
 1994 26.00867 
 1995 26.24801 
 1996 26.05568 
 1997 26.57155 
 1998  26.5698 
 1999 26.25455 
 2000 26.17099 
 2001 26.44254 
 2002  26.5461 
 2003 26.64142 
 2004 26.54679 
 2005 26.51494 
 2006 26.45163 
 2007 26.47598 
 2008 26.42754 
 2009 26.67433 
 2010 26.84027 
 2011 26.37886 
 2012 26.61373 
 2013 26.40948 
 2014 26.53142 
 2015 26.94234 
 2016  26.7787 
 2017 26.62688 
 2018 26.55453