# year    value 
 1901 -11.06727 
 1902 -12.1796 
 1903 -11.2918 
 1904 -11.35685 
 1905 -11.12266 
 1906 -11.04895 
 1907 -11.58301 
 1908 -11.31601 
 1909 -11.89402 
 1910 -11.56405 
 1911 -11.38758 
 1912 -11.39071 
 1913 -11.40262 
 1914 -10.87822 
 1915 -11.63366 
 1916 -11.76907 
 1917 -11.38717 
 1918 -11.59683 
 1919 -11.67424 
 1920 -11.29222 
 1921 -10.9558 
 1922 -11.51763 
 1923 -11.01578 
 1924 -11.0201 
 1925 -10.95668 
 1926 -10.11028 
 1927 -11.04191 
 1928 -10.8077 
 1929 -11.04026 
 1930 -10.86664 
 1931 -11.11658 
 1932 -11.0276 
 1933 -11.57835 
 1934 -10.31267 
 1935 -10.98829 
 1936 -10.84881 
 1937 -10.33568 
 1938 -10.20446 
 1939 -10.57423 
 1940 -10.31477 
 1941 -11.07151 
 1942  -10.609 
 1943 -9.748466 
 1944 -10.06619 
 1945 -10.53179 
 1946 -11.57835 
 1947 -10.4186 
 1948 -10.74456 
 1949 -10.78053 
 1950 -11.36643 
 1951 -11.07326 
 1952 -11.3827 
 1953 -10.30506 
 1954 -10.84569 
 1955 -11.58664 
 1956 -11.54193 
 1957 -10.82847 
 1958  -11.358 
 1959 -10.7242 
 1960 -10.76461 
 1961  -11.403 
 1962 -10.4087 
 1963 -10.4979 
 1964 -11.8039 
 1965 -11.73349 
 1966 -12.09834 
 1967 -10.67523 
 1968 -11.07713 
 1969 -11.25534 
 1970 -11.09815 
 1971 -11.23521 
 1972  -11.768 
 1973 -10.97758 
 1974 -11.54274 
 1975 -10.74705 
 1976 -11.25978 
 1977 -10.89305 
 1978 -10.46158 
 1979 -11.37144 
 1980 -10.58989 
 1981 -9.538896 
 1982 -11.44548 
 1983 -10.40847 
 1984 -10.89264 
 1985 -10.72562 
 1986 -10.43275 
 1987 -11.24734 
 1988 -9.924912 
 1989 -10.3026 
 1990 -10.39921 
 1991 -9.973163 
 1992 -10.84252 
 1993 -10.08309 
 1994 -10.56906 
 1995 -9.418967 
 1996 -10.55986 
 1997 -9.754215 
 1998 -10.38508 
 1999 -10.84793 
 2000  -10.013 
 2001 -10.08583 
 2002 -9.556566 
 2003 -9.318084 
 2004 -10.27764 
 2005  -9.1205 
 2006 -10.01697 
 2007 -9.105056 
 2008 -9.796147 
 2009 -10.07738 
 2010 -9.496651 
 2011 -9.367002 
 2012 -9.944675 
 2013 -9.673978 
 2014 -9.015287 
 2015 -9.051322 
 2016 -8.437692 
 2017 -8.868971 
 2018 -9.06499