# year    value 
 1901 -26.90112 
 1902 -26.81179 
 1903 -26.55019 
 1904 -26.85748 
 1905 -25.68965 
 1906 -27.28684 
 1907 -26.86092 
 1908 -27.15879 
 1909 -27.35091 
 1910 -26.48199 
 1911 -27.3568 
 1912 -26.39263 
 1913 -27.35523 
 1914 -25.74463 
 1915 -26.57281 
 1916 -26.91834 
 1917 -27.76881 
 1918 -27.29837 
 1919 -27.95298 
 1920 -26.0146 
 1921 -26.21527 
 1922 -27.36451 
 1923 -26.10067 
 1924 -26.47441 
 1925 -25.93642 
 1926 -25.39544 
 1927 -26.52703 
 1928 -25.6972 
 1929 -25.55598 
 1930 -26.05636 
 1931 -26.42197 
 1932 -25.54767 
 1933 -26.80256 
 1934 -25.19984 
 1935 -24.79766 
 1936 -26.8023 
 1937 -24.56779 
 1938 -25.51535 
 1939 -25.89552 
 1940 -24.56853 
 1941 -26.71228 
 1942 -25.81831 
 1943 -24.99495 
 1944 -24.16711 
 1945 -24.47944 
 1946 -26.99909 
 1947 -26.50726 
 1948 -25.52629 
 1949 -26.37784 
 1950 -26.77384 
 1951 -27.19504 
 1952 -25.99645 
 1953 -25.95643 
 1954 -26.38158 
 1955 -25.87959 
 1956 -27.12447 
 1957 -25.5988 
 1958 -26.42153 
 1959 -25.82583 
 1960 -26.19903 
 1961 -25.02711 
 1962 -25.23093 
 1963 -24.90321 
 1964 -25.5558 
 1965 -27.17217 
 1966 -28.91616 
 1967 -26.53564 
 1968 -25.57873 
 1969 -28.22649 
 1970 -25.66616 
 1971 -26.86511 
 1972 -27.32055 
 1973 -25.86004 
 1974 -26.94975 
 1975 -26.20929 
 1976 -26.39835 
 1977 -25.74241 
 1978 -25.52889 
 1979 -27.97653 
 1980 -25.10232 
 1981 -23.81857 
 1982 -25.8169 
 1983 -25.47306 
 1984 -25.22376 
 1985 -26.70772 
 1986 -24.70019 
 1987 -26.36341 
 1988 -25.36842 
 1989 -24.65878 
 1990 -26.49529 
 1991 -25.92097 
 1992 -25.11123 
 1993 -24.24884 
 1994 -26.78429 
 1995 -23.92265 
 1996 -25.10358 
 1997 -25.53809 
 1998 -26.02165 
 1999 -25.47756 
 2000 -24.53607 
 2001 -25.63874 
 2002 -24.95743 
 2003 -24.59324 
 2004 -24.63335 
 2005 -24.97251 
 2006 -24.4919 
 2007 -23.51896 
 2008 -24.06303 
 2009 -25.19784 
 2010 -25.14471 
 2011 -24.77108 
 2012 -23.71033 
 2013 -25.62299 
 2014 -24.00424 
 2015 -23.41381 
 2016 -22.46437 
 2017 -23.84278 
 2018 -23.28461