1880 13.72 1881 13.80 1882 13.74 1883 13.73 1884 13.69 1885 13.70 1886 13.73 1887 13.65 1888 13.72 1889 13.83 1890 13.60 1891 13.72 1892 13.67 1893 13.66 1894 13.65 1895 13.73 1896 13.82 1897 13.86 1898 13.73 1899 13.84 1900 13.91 1901 13.85 1902 13.75 1903 13.69 1904 13.65 1905 13.74 1906 13.81 1907 13.60 1908 13.66 1909 13.65 1910 13.66 1911 13.66 1912 13.68 1913 13.70 1914 13.86 1915 13.90 1916 13.71 1917 13.62 1918 13.67 1919 13.79 1920 13.80 1921 13.85 1922 13.75 1923 13.78 1924 13.78 1925 13.83 1926 13.98 1927 13.85 1928 13.87 1929 13.73 1930 13.92 1931 13.97 1932 13.92 1933 13.80 1934 13.92 1935 13.87 1936 13.94 1937 14.06 1938 14.10 1939 14.01 1940 14.03 1941 14.09 1942 14.02 1943 14.08 1944 14.19 1945 14.06 1946 13.94 1947 13.99 1948 13.95 1949 13.93 1950 13.84 1951 13.96 1952 14.02 1953 14.10 1954 13.89 1955 13.89 1956 13.81 1957 14.08 1958 14.08 1959 14.06 1960 13.99 1961 14.07 1962 14.04 1963 14.08 1964 13.79 1965 13.89 1966 13.97 1967 14.00 1968 13.96 1969 14.08 1970 14.03 1971 13.89 1972 14.00 1973 14.14 1974 13.92 1975 13.96 1976 13.85 1977 14.13 1978 14.04 1979 14.10 1980 14.20 1981 14.27 1982 14.05 1983 14.26 1984 14.10 1985 14.05 1986 14.13 1987 14.28 1988 14.33 1989 14.21 1990 14.36 1991 14.35 1992 14.13 1993 14.14 1994 14.24 1995 14.39 1996 14.30 1997 14.41 1998 14.58 1999 14.33 2000 14.35 2001 14.48 2002 14.56 2003 14.56 2004 14.48 2005 14.62 2006 14.55 2007 14.58 2008 14.44 2009 14.57 2010 14.63 2011 14.52 2012 14.55 2013 14.61