# year value 1900 15.70798 1901 15.54821 1902 15.60163 1903 15.18628 1904 15.37727 1905 15.45315 1906 15.53583 1907 15.36906 1908 15.43201 1909 15.58062 1910 15.58467 1911 15.55617 1912 15.37261 1913 15.28031 1914 15.48736 1915 15.55907 1916 15.54627 1917 15.67555 1918 15.79623 1919 15.65287 1920 15.74332 1921 15.69257 1922 15.65341 1923 15.70417 1924 15.74031 1925 15.72616 1926 15.73186 1927 15.75203 1928 15.80616 1929 15.78693 1930 15.69857 1931 15.72143 1932 15.74889 1933 15.73709 1934 15.64459 1935 15.72167 1936 15.83125 1937 15.83461 1938 15.88919 1939 15.74144 1940 15.90308 1941 15.79595 1942 15.84018 1943 15.93317 1944 15.89846 1945 15.92383 1946 15.73257 1947 15.89936 1948 15.87101 1949 15.89077 1950 15.86112 1951 15.80266 1952 15.76552 1953 15.67883 1954 15.80623 1955 15.80232 1956 15.84984 1957 15.806 1958 15.80566 1959 15.70536 1960 15.81531 1961 15.79691 1962 15.80743 1963 15.77912 1964 15.63331 1965 15.66721 1966 15.67725 1967 15.77745 1968 15.71972 1969 15.68046 1970 15.80421 1971 15.86274 1972 15.86615 1973 15.85654 1974 15.81054 1975 15.92159 1976 15.91412 1977 15.86205 1978 15.98574 1979 16.03777 1980 16.15989 1981 16.08194 1982 15.99492 1983 15.65444 1984 15.91745 1985 16.08994 1986 15.98456 1987 16.11754 1988 16.13118 1989 16.23264 1990 16.27094 1991 16.26911 1992 15.83605 1993 16.04485 1994 16.16918 1995 16.19525 1996 16.3631 1997 16.43379 1998 16.43869 1999 16.52328 2000 16.60342 2001 16.70172 2002 16.59154 2003 16.6194 2004 16.64374 2005 16.77385