# year    value 
 1901 10.62605 
 1902 10.19423 
 1903 10.10089 
 1904 10.33073 
 1905 10.03425 
 1906 10.17144 
 1907 9.935792 
 1908 10.11992 
 1909 10.07402 
 1910 10.24047 
 1911 10.10744 
 1912  10.4678 
 1913 10.66964 
 1914 10.41582 
 1915 10.40616 
 1916 10.47984 
 1917 10.54345 
 1918 10.27301 
 1919 10.62593 
 1920 10.47322 
 1921 10.23561 
 1922 10.38619 
 1923 10.14994 
 1924 10.24113 
 1925 10.15915 
 1926 10.33463 
 1927 10.38512 
 1928 10.27026 
 1929 10.36319 
 1930 10.39923 
 1931 10.11467 
 1932 10.48746 
 1933 10.27551 
 1934 10.27293 
 1935 10.23825 
 1936 10.16522 
 1937 10.25376 
 1938 10.34109 
 1939 10.29464 
 1940  10.3572 
 1941  10.2551 
 1942 10.42037 
 1943 10.32799 
 1944 10.62165 
 1945 10.73059 
 1946 10.29982 
 1947 10.48649 
 1948 10.24163 
 1949 10.41906 
 1950 10.33536 
 1951 10.46605 
 1952 10.68973 
 1953 10.56131 
 1954  10.4013 
 1955 10.22746 
 1956  10.2621 
 1957 10.49971 
 1958 10.55152 
 1959 10.34285 
 1960 10.59909 
 1961 10.38393 
 1962 10.76306 
 1963 10.33132 
 1964 10.18759 
 1965 10.35432 
 1966 10.37762 
 1967  10.4742 
 1968 10.59248 
 1969 10.62649 
 1970 10.53213 
 1971 10.21317 
 1972 10.34922 
 1973 10.49252 
 1974 10.32782 
 1975 10.46856 
 1976  10.0779 
 1977 10.68697 
 1978 10.71179 
 1979 10.78819 
 1980  10.7874 
 1981 10.72385 
 1982 10.62592 
 1983  10.7248 
 1984 10.18698 
 1985 10.91612 
 1986 10.65081 
 1987 10.94671 
 1988 10.71186 
 1989 10.90215 
 1990 10.81833 
 1991 10.57287 
 1992 10.35061 
 1993 10.73818 
 1994 10.77443 
 1995 10.56073 
 1996 10.57375 
 1997 10.76199 
 1998 11.19751 
 1999 11.03104 
 2000 10.41176 
 2001 10.72472 
 2002 10.58242 
 2003 10.92606 
 2004 11.02826 
 2005 10.86933 
 2006 10.90189 
 2007  10.6691 
 2008 11.10382 
 2009 11.03736 
 2010 10.86894 
 2011 10.95605 
 2012  10.9626 
 2013 11.26085 
 2014 11.13141 
 2015 11.17611 
 2016 11.41663 
 2017 11.33874 
 2018 11.23333