# year    value 
 1901 12.37599 
 1902 11.58031 
 1903 11.23685 
 1904 12.73514 
 1905 11.92298 
 1906 11.48436 
 1907 11.82644 
 1908 11.80655 
 1909  12.2882 
 1910 12.47412 
 1911  10.6981 
 1912 11.35087 
 1913  11.9146 
 1914 12.98547 
 1915 12.26757 
 1916 11.04157 
 1917 12.18652 
 1918 11.56295 
 1919 10.35965 
 1920 11.84962 
 1921  12.4845 
 1922 12.72655 
 1923 11.96516 
 1924 12.23633 
 1925 10.88465 
 1926 11.48628 
 1927 12.39446 
 1928 11.81356 
 1929   10.831 
 1930 11.63663 
 1931 13.27637 
 1932 11.22561 
 1933 13.18434 
 1934 12.98391 
 1935 11.06307 
 1936 11.81872 
 1937  12.2654 
 1938 12.78055 
 1939 13.08826 
 1940 12.46465 
 1941 12.16427 
 1942  11.9372 
 1943 12.09092 
 1944 12.35867 
 1945 11.87915 
 1946 11.20811 
 1947 12.53511 
 1948 12.27098 
 1949    12.76 
 1950 12.19571 
 1951 10.93627 
 1952 11.98211 
 1953 13.43603 
 1954 13.22822 
 1955 11.46751 
 1956  12.6365 
 1957 11.08736 
 1958 12.65563 
 1959 10.63107 
 1960 12.69781 
 1961 11.01154 
 1962 12.99133 
 1963 14.35678 
 1964  11.8271 
 1965 12.01751 
 1966 11.97306 
 1967  12.2689 
 1968 11.92946 
 1969 11.70474 
 1970 11.09748 
 1971 11.76895 
 1972 10.85335 
 1973 11.99259 
 1974 11.74744 
 1975 11.71378 
 1976 10.74602 
 1977 12.45039 
 1978 12.08467 
 1979 12.23838 
 1980  12.4254 
 1981 12.72112 
 1982 11.42598 
 1983 12.72182 
 1984 11.20716 
 1985 10.03729 
 1986 11.19483 
 1987 12.40266 
 1988 12.23511 
 1989 12.12154 
 1990 13.08215 
 1991 11.18396 
 1992 11.73266 
 1993 10.58612 
 1994 12.62186 
 1995 12.17732 
 1996 11.00019 
 1997 12.16086 
 1998 13.44273 
 1999 12.86856 
 2000 11.20146 
 2001 13.12053 
 2002 11.32127 
 2003 12.07678 
 2004 12.61921 
 2005 13.30987 
 2006 11.66283 
 2007 13.03133 
 2008 12.42657 
 2009 12.27451 
 2010 12.69321 
 2011 12.78128 
 2012 12.76726 
 2013 12.33594 
 2014 12.33767 
 2015 13.88817 
 2016 14.37417 
 2017 13.07565 
 2018 11.53303