# year    value 
 1901 -12.21921 
 1902 -14.16538 
 1903 -12.82389 
 1904 -12.28288 
 1905 -12.06821 
 1906 -11.96252 
 1907 -12.62767 
 1908 -13.01701 
 1909 -13.40296 
 1910 -13.02573 
 1911 -13.10758 
 1912 -12.63804 
 1913 -12.47022 
 1914 -13.28987 
 1915 -12.14019 
 1916 -13.2392 
 1917 -12.66766 
 1918 -13.19609 
 1919 -13.11181 
 1920 -11.86375 
 1921 -12.35308 
 1922 -12.67762 
 1923 -13.07912 
 1924 -11.99498 
 1925 -12.6561 
 1926 -11.68541 
 1927 -12.68203 
 1928 -12.55605 
 1929 -12.8588 
 1930 -12.43247 
 1931 -12.85874 
 1932 -11.61171 
 1933 -12.91677 
 1934 -12.37369 
 1935 -12.61247 
 1936 -12.14793 
 1937 -12.33692 
 1938 -11.27163 
 1939 -11.95188 
 1940 -11.33669 
 1941 -12.92484 
 1942 -12.86981 
 1943 -10.55974 
 1944 -11.65804 
 1945 -12.09164 
 1946 -12.31032 
 1947 -11.65534 
 1948 -11.86009 
 1949 -11.73742 
 1950 -12.11623 
 1951 -12.29659 
 1952 -12.50228 
 1953 -10.79412 
 1954 -11.78823 
 1955 -13.19615 
 1956 -12.99094 
 1957 -12.43887 
 1958 -13.13304 
 1959 -12.38572 
 1960 -12.65397 
 1961 -12.87711 
 1962 -11.69492 
 1963 -13.06864 
 1964 -14.3431 
 1965 -11.82125 
 1966 -13.71302 
 1967 -11.41016 
 1968 -11.27069 
 1969 -13.20622 
 1970 -12.47815 
 1971 -12.68259 
 1972 -12.98627 
 1973 -12.04954 
 1974 -12.19949 
 1975 -11.25545 
 1976 -12.09047 
 1977 -11.80866 
 1978 -12.51371 
 1979 -12.83406 
 1980 -11.99622 
 1981 -11.38393 
 1982 -12.52288 
 1983 -12.53204 
 1984 -11.9575 
 1985 -12.71763 
 1986 -12.28551 
 1987 -12.87461 
 1988 -11.40953 
 1989 -11.50894 
 1990 -9.563576 
 1991 -11.38718 
 1992 -12.07425 
 1993 -11.14481 
 1994 -11.46199 
 1995 -10.62481 
 1996 -11.18949 
 1997 -10.68071 
 1998 -11.30787 
 1999 -12.09719 
 2000 -10.69097 
 2001 -11.64031 
 2002 -11.17891 
 2003 -10.6863 
 2004 -11.84971 
 2005 -10.29527 
 2006 -11.38397 
 2007 -10.3506 
 2008 -11.03091 
 2009 -11.54235 
 2010 -9.993237 
 2011 -9.815416 
 2012 -10.80483 
 2013 -11.39751 
 2014 -9.976148 
 2015 -10.26206 
 2016 -9.256727 
 2017 -10.08762 
 2018 -11.35814