# year    value 
 1901 24.06762 
 1902 24.32071 
 1903 24.17494 
 1904 23.86412 
 1905  24.0832 
 1906 24.29026 
 1907  23.8879 
 1908 23.96045 
 1909 23.87085 
 1910 23.92496 
 1911 23.82176 
 1912 24.30246 
 1913 23.81239 
 1914 24.29984 
 1915 24.34212 
 1916 24.05191 
 1917 23.50033 
 1918 23.62467 
 1919 24.26478 
 1920 23.89111 
 1921 24.02087 
 1922 24.06926 
 1923 24.08191 
 1924 23.88494 
 1925   23.886 
 1926 24.16261 
 1927 23.92581 
 1928 24.24708 
 1929 23.62729 
 1930 24.00473 
 1931 24.15842 
 1932 24.09659 
 1933 24.23413 
 1934 24.07337 
 1935 23.87193 
 1936 24.04071 
 1937 23.99322 
 1938 24.31799 
 1939  24.0636 
 1940 24.06892 
 1941 24.36083 
 1942 24.43826 
 1943 24.09649 
 1944 23.86543 
 1945 24.10845 
 1946 24.02515 
 1947 24.10223 
 1948 23.95805 
 1949 23.87487 
 1950  23.9233 
 1951 23.91791 
 1952 24.15697 
 1953 24.20285 
 1954 24.05337 
 1955 23.77841 
 1956 23.68409 
 1957 24.14538 
 1958 24.61921 
 1959 24.30967 
 1960 23.67414 
 1961 24.36186 
 1962 23.90946 
 1963 24.03008 
 1964 24.29457 
 1965 23.97931 
 1966 24.21205 
 1967 24.11566 
 1968  23.6559 
 1969  24.4937 
 1970 24.37373 
 1971 23.82914 
 1972 24.03451 
 1973 24.67788 
 1974 23.65717 
 1975 23.89267 
 1976 23.60888 
 1977  23.9557 
 1978 24.12408 
 1979 24.10924 
 1980 24.59613 
 1981 24.31277 
 1982 24.04952 
 1983 24.67765 
 1984 24.19977 
 1985 24.32911 
 1986 24.59468 
 1987 24.62434 
 1988 24.60159 
 1989 24.14398 
 1990 24.59368 
 1991 24.52673 
 1992 24.79129 
 1993 24.64526 
 1994 24.41198 
 1995 24.33979 
 1996 24.33415 
 1997 24.17377 
 1998  25.0822 
 1999 24.37842 
 2000 24.16365 
 2001 24.42869 
 2002 25.00311 
 2003 24.71789 
 2004 24.65061 
 2005 25.11007 
 2006 24.26912 
 2007 24.73134 
 2008 24.18176 
 2009  24.5857 
 2010 24.91954 
 2011 24.20491 
 2012 24.32656 
 2013 24.71452 
 2014 24.78681 
 2015 24.67171 
 2016 25.14885 
 2017 24.82867 
 2018 24.88752