YEAR VALUE 1896 33.93 1897 33.32 1898 33.1 1899 28.84 1900 33.01 1901 32.92 1902 31.81 1903 30.96 1904 30.62 1905 29.39 1906 33.35 1907 34.71 1908 34.19 1909 34.27 1910 28.99 1911 33.66 1912 30.19 1913 31.88 1914 33.43 1915 31.37 1916 32.25 1917 29.95 1918 29.96 1919 33.64 1920 31.28 1921 35.55 1922 32.05 1923 33.35 1924 33.31 1925 32.42 1926 34.35 1927 34.41 1928 32.36 1929 29.58 1930 33.36 1931 34.95 1932 35.35 1933 32.04 1934 36.12 1935 34.27 1936 28.67 1937 31.29 1938 34.49 1939 33.68 1940 32.66 1941 34.92 1942 33.24 1943 33.8 1944 34.07 1945 33.05 1946 32.76 1947 34.05 1948 31.78 1949 31.19 1950 34.08 1951 33.49 1952 33.88 1953 36.17 1954 36.19 1955 32.42 1956 32.46 1957 34.64 1958 34.45 1959 32.21 1960 32.89 1961 33.36 1962 31.81 1963 31.44 1964 31.19 1965 32.84 1966 31.91 1967 33.66 1968 32.08 1969 31.41 1970 32.73 1971 32.9 1972 33.22 1973 31.74 1974 33.85 1975 33.59 1976 35.19 1977 30.66 1978 29.6 1979 27.22 1980 33.9 1981 35.34 1982 31.29 1983 35.88 1984 31.09 1985 31.1 1986 33.57 1987 35.02 1988 32.55 1989 32.66 1990 34.18 1991 33.8 1992 36.83 1993 31.53 1994 32.39 1995 36.1 1996 33.48 1997 33.93 1998 36.49 1999 36.84 2000 36.95 2001 31.75