# year    value 
 1901 7.226778 
 1902 6.901029 
 1903 8.117153 
 1904 6.722473 
 1905 6.799422 
 1906 8.211776 
 1907 8.759192 
 1908 6.535375 
 1909 7.470899 
 1910 6.882788 
 1911 8.851225 
 1912 5.130346 
 1913 8.563016 
 1914 6.899391 
 1915 5.597064 
 1916 7.264853 
 1917 7.781955 
 1918 7.350965 
 1919 6.681538 
 1920 6.998703 
 1921 7.966312 
 1922  5.79011 
 1923 8.526982 
 1924 7.930771 
 1925 6.945076 
 1926 9.819045 
 1927 8.125859 
 1928  8.30197 
 1929 9.022599 
 1930 8.620453 
 1931 6.602674 
 1932 9.102967 
 1933 7.714426 
 1934 8.249559 
 1935 8.524338 
 1936 6.618774 
 1937 7.737991 
 1938 8.649382 
 1939 7.732102 
 1940 8.189524 
 1941 6.568369 
 1942 9.257842 
 1943 8.641381 
 1944  7.37392 
 1945 7.819615 
 1946 7.840676 
 1947 9.253614 
 1948 8.481231 
 1949 9.359072 
 1950 7.865729 
 1951 8.873355 
 1952 6.614729 
 1953 8.712414 
 1954 8.296693 
 1955 7.420661 
 1956 7.409199 
 1957  8.04458 
 1958 8.719322 
 1959 7.813841 
 1960  8.13058 
 1961 9.512588 
 1962 7.850946 
 1963 9.169199 
 1964 8.142946 
 1965 7.457608 
 1966 8.596248 
 1967 8.944952 
 1968 8.399996 
 1969 8.833022 
 1970  8.57318 
 1971 7.393911 
 1972  6.55397 
 1973 7.769237 
 1974 6.712204 
 1975 8.162878 
 1976 7.872624 
 1977 8.085975 
 1978 7.266992 
 1979 8.062278 
 1980 7.707079 
 1981 8.129369 
 1982  9.40627 
 1983 8.167122 
 1984 8.500359 
 1985  8.07509 
 1986 8.800855 
 1987 9.633487 
 1988 7.929834 
 1989 7.952329 
 1990 8.452211 
 1991 8.465676 
 1992 8.387602 
 1993 7.323527 
 1994 9.172878 
 1995 8.189665 
 1996 7.610372 
 1997 8.777164 
 1998 7.519367 
 1999  8.81098 
 2000 9.543548 
 2001  8.21668 
 2002 8.784986 
 2003 8.269821 
 2004 9.156614 
 2005 8.873271 
 2006 10.73853 
 2007 7.397082 
 2008 8.439035 
 2009 9.499186 
 2010  8.03589 
 2011 9.754057 
 2012 9.629372 
 2013 9.192065 
 2014 10.46792 
 2015 9.039919 
 2016 9.106906 
 2017 8.352505 
 2018 10.39412