# year    value 
 1901  13.1198 
 1902 12.70936 
 1903 12.70044 
 1904 12.67106 
 1905 12.65029 
 1906 13.10505 
 1907  12.5099 
 1908 12.61014 
 1909 12.48566 
 1910 12.79778 
 1911 12.54914 
 1912 12.73979 
 1913 12.63278 
 1914 12.88163 
 1915  12.9677 
 1916 12.68145 
 1917 12.38679 
 1918 12.51943 
 1919 12.73371 
 1920 12.94802 
 1921 13.04844 
 1922 12.96823 
 1923 12.66062 
 1924 12.85815 
 1925 12.95911 
 1926 12.98322 
 1927 12.77448 
 1928 12.83727 
 1929  12.7411 
 1930 12.98878 
 1931 12.83113 
 1932 12.97751 
 1933 12.74466 
 1934 12.96411 
 1935 12.81081 
 1936 12.93581 
 1937    12.86 
 1938 13.43831 
 1939  13.0035 
 1940 13.13078 
 1941 13.07226 
 1942 13.01815 
 1943 13.15416 
 1944 13.15071 
 1945 13.00807 
 1946 13.11844 
 1947 13.23386 
 1948  13.0241 
 1949 12.98148 
 1950 12.89627 
 1951 12.93459 
 1952 12.93836 
 1953  13.3628 
 1954 12.77374 
 1955 12.61462 
 1956 12.50396 
 1957 12.77491 
 1958 13.12677 
 1959 13.17494 
 1960 12.53344 
 1961 13.20008 
 1962 13.14331 
 1963 12.83991 
 1964 12.68588 
 1965 12.80132 
 1966 12.88291 
 1967 13.10556 
 1968 13.13583 
 1969 12.95394 
 1970 12.97758 
 1971 12.74909 
 1972 12.88041 
 1973 13.40977 
 1974 12.93698 
 1975 13.21423 
 1976 12.67656 
 1977 13.41641 
 1978 13.14035 
 1979 12.99578 
 1980  13.2419 
 1981 13.56828 
 1982 13.01534 
 1983 13.25976 
 1984 13.20848 
 1985  13.1503 
 1986 13.38832 
 1987 13.15041 
 1988 13.56221 
 1989 13.39622 
 1990 13.96011 
 1991 13.51938 
 1992 13.34351 
 1993 13.46662 
 1994  13.5934 
 1995 13.59701 
 1996 13.24177 
 1997 13.53139 
 1998 13.97356 
 1999 13.49769 
 2000 13.91951 
 2001 13.89688 
 2002 13.89188 
 2003 13.76678 
 2004 13.80871 
 2005 14.08869 
 2006 13.79045 
 2007 14.13742 
 2008 13.97043 
 2009 13.80978 
 2010  14.2557 
 2011 13.88026 
 2012 14.06912 
 2013 13.83502 
 2014 14.11122 
 2015 14.15313 
 2016 14.66578 
 2017 14.29441 
 2018 14.10855