# year    value 
 1901 -7.870842 
 1902 -6.69397 
 1903 -7.063818 
 1904 -7.937996 
 1905 -7.619466 
 1906 -7.396743 
 1907 -7.604275 
 1908 -7.324884 
 1909 -7.818476 
 1910 -7.217165 
 1911 -7.96785 
 1912 -7.320067 
 1913 -7.710398 
 1914 -5.955743 
 1915 -7.217978 
 1916 -6.807921 
 1917 -8.246344 
 1918 -7.841982 
 1919 -7.686519 
 1920 -7.632587 
 1921 -6.965569 
 1922 -7.990331 
 1923 -7.525297 
 1924 -7.299819 
 1925 -7.164575 
 1926 -6.187511 
 1927 -7.525186 
 1928 -7.704719 
 1929 -8.990072 
 1930 -8.047175 
 1931 -7.766089 
 1932 -6.702279 
 1933 -8.07423 
 1934 -7.239292 
 1935 -6.706777 
 1936 -8.08971 
 1937 -7.386036 
 1938 -7.206511 
 1939 -7.210656 
 1940 -6.976882 
 1941 -6.646402 
 1942 -7.855611 
 1943 -7.284685 
 1944 -6.144132 
 1945 -8.575451 
 1946  -6.8474 
 1947 -8.288204 
 1948 -6.800711 
 1949 -6.868886 
 1950 -8.124414 
 1951 -7.939958 
 1952 -6.453202 
 1953 -6.794842 
 1954 -7.566439 
 1955 -6.856307 
 1956 -7.740599 
 1957 -7.777686 
 1958 -5.765248 
 1959 -6.870378 
 1960 -6.54741 
 1961 -6.442755 
 1962 -6.61948 
 1963 -6.736056 
 1964 -7.529222 
 1965 -7.364444 
 1966 -6.586933 
 1967 -7.81329 
 1968 -7.397835 
 1969 -8.975922 
 1970 -6.892094 
 1971 -7.314163 
 1972 -7.927488 
 1973 -6.991567 
 1974 -7.220086 
 1975 -6.575076 
 1976 -6.632549 
 1977 -7.931255 
 1978 -7.284591 
 1979 -7.430531 
 1980 -6.608949 
 1981 -5.888371 
 1982 -6.859475 
 1983 -5.624957 
 1984 -6.947229 
 1985 -8.059731 
 1986 -6.631189 
 1987 -6.091691 
 1988 -6.361084 
 1989 -5.983082 
 1990 -5.800512 
 1991 -6.266055 
 1992 -5.746605 
 1993 -6.357872 
 1994 -6.812675 
 1995 -5.407009 
 1996 -6.972632 
 1997  -6.0777 
 1998 -5.555779 
 1999 -4.939653 
 2000 -5.405394 
 2001 -6.450172 
 2002 -4.753248 
 2003 -6.619384 
 2004 -5.317291 
 2005 -6.656979 
 2006 -6.196846 
 2007 -4.733739 
 2008 -6.675181 
 2009 -6.120774 
 2010 -6.814981 
 2011 -6.802355 
 2012 -6.66043 
 2013 -6.433641 
 2014 -6.369903 
 2015 -5.175203 
 2016 -4.442289 
 2017 -5.274038 
 2018 -5.963971