# year    value 
 1901 -3.114014 
 1902 -2.189293 
 1903 -2.765233 
 1904 -2.910013 
 1905 -3.187851 
 1906 -3.083651 
 1907 -2.335757 
 1908 -2.706336 
 1909 -2.777565 
 1910 -2.441171 
 1911 -3.006423 
 1912 -2.494579 
 1913 -2.692318 
 1914 -2.059964 
 1915 -2.723516 
 1916 -2.389719 
 1917 -2.674592 
 1918 -3.12634 
 1919 -3.298907 
 1920 -2.847108 
 1921 -2.711128 
 1922 -2.183025 
 1923 -2.620065 
 1924 -2.389989 
 1925 -3.24859 
 1926 -1.914384 
 1927 -2.931336 
 1928 -2.206321 
 1929 -3.202104 
 1930 -3.838778 
 1931 -3.00295 
 1932 -2.515038 
 1933 -3.211549 
 1934 -2.544103 
 1935 -2.329526 
 1936 -3.572071 
 1937 -2.751419 
 1938 -2.763598 
 1939 -2.162398 
 1940 -1.852329 
 1941 -1.305726 
 1942 -2.069486 
 1943 -2.634023 
 1944 -2.252208 
 1945 -4.486821 
 1946 -1.320707 
 1947 -2.73865 
 1948 -2.383766 
 1949 -2.119246 
 1950 -3.055533 
 1951 -3.722288 
 1952 -1.701285 
 1953 -2.561846 
 1954 -2.324999 
 1955 -3.477024 
 1956 -2.686071 
 1957 -3.81454 
 1958 -2.051325 
 1959 -2.390518 
 1960 -1.980596 
 1961 -2.732617 
 1962 -2.896415 
 1963 -2.605291 
 1964 -3.430993 
 1965 -2.48877 
 1966 -1.596126 
 1967 -3.109123 
 1968 -3.808667 
 1969 -3.014584 
 1970 -2.262439 
 1971 -2.776646 
 1972 -2.869786 
 1973 -1.953827 
 1974 -3.101145 
 1975 -2.960553 
 1976 -2.485087 
 1977 -3.311487 
 1978 -2.823802 
 1979 -1.281065 
 1980 -2.15916 
 1981 -1.75641 
 1982 -2.265697 
 1983 -3.089227 
 1984 -3.218014 
 1985 -2.532993 
 1986 -2.273136 
 1987 -1.278806 
 1988 -1.604002 
 1989 -2.034477 
 1990 -1.463871 
 1991 -1.903799 
 1992 -2.338774 
 1993 -1.788839 
 1994 -1.795927 
 1995 -2.309239 
 1996 -2.478843 
 1997 -2.053288 
 1998 -1.946735 
 1999 -0.609877 
 2000 -2.246221 
 2001 -1.278567 
 2002 -1.172921 
 2003 -1.427603 
 2004 -1.283584 
 2005 -1.930652 
 2006 -1.137455 
 2007 -1.09822 
 2008 -2.861642 
 2009 -0.5405466 
 2010 -1.172117 
 2011 -2.169721 
 2012 -2.736727 
 2013 -1.718869 
 2014 -2.044034 
 2015 -1.446692 
 2016 -1.498815 
 2017 -0.553894 
 2018 -1.400905