| 1900 | $20.67 |  | 1901 | $20.67 |  | 1902 | $20.67 |  | 1903 | $20.67 |  | 1904 | $20.67 |  | 1905 | $20.67 |  | 1906 | $20.67 |  | 1907 | $20.67 |  | 1908 | $20.67 |  | 1909 | $20.67 |  | 1910 | $20.67 |  | 1911 | $20.67 |  | 1912 | $20.67 |  | 1913 | $20.67 |  | 1914 | $20.67 |  | 1915 | $20.67 |  | 1916 | $20.67 |  | 1917 | $20.67 |  | 1918 | $20.67 |  | 1919 | $20.67 |  | 1920 | $20.67 |  | 1921 | $20.67 |  | 1922 | $20.67 |  | 1923 | $20.67 |  | 1924 | $20.67 |  | 1925 | $20.67 |  | 1926 | $20.67 |  | 1927 | $20.67 |  | 1928 | $20.67 |  | 1929 | $20.67 |  
  | | 1930 | $20.67 |  | 1931 | $20.67 |  | 1932 | $20.67 |  | 1933 | $32.32 |  | 1934 | $35.00 |  | 1935 | $35.00 |  | 1936 | $35.00 |  | 1937 | $35.00 |  | 1938 | $35.00 |  | 1939 | $35.00 |  | 1940 | $34.50 |  | 1941 | $35.50 |  | 1942 | $35.50 |  | 1943 | $36.50 |  | 1944 | $36.25 |  | 1945 | $37.25 |  | 1946 | $38.25 |  | 1947 | $43.00 |  | 1948 | $42.00 |  | 1949 | $40.50 |  | 1950 | $40.25 |  | 1951 | $40.00 |  | 1952 | $38.70 |  | 1953 | $35.50 |  | 1954 | $35.25 |  | 1955 | $35.15 |  | 1956 | $35.20 |  | 1957 | $35.25 |  | 1958 | $35.25 |  | 1959 | $35.25 |  
  | | 1960 | $36.50 |  | 1961 | $35.50 |  | 1962 | $35.35 |  | 1963 | $35.25 |  | 1964 | $35.35 |  | 1965 | $35.50 |  | 1966 | $35.40 |  | 1967 | $35.50 |  | 1968 | $43.50 |  | 1969 | $35.40 |  | 1970 | $37.60 |  | 1971 | $43.80 |  | 1972 | $65.20 |  | 1973 | $114.50 |  | 1974 | $195.20 |  | 1975 | $150.80 |  | 1976 | $145.10 |  | 1977 | $179.20 |  | 1978 | $244.90 |  | 1979 | $578.70 |  | 1980 | $641.20 |  | 1981 | $430.80 |  | 1982 | $484.50 |  | 1983 | $415.00 |  | 1984 | $331.30 |  | 1985 | $354.20 |  | 1986 | $435.20 |  | 1987 | $522.90 |  | 1988 | $441.00 |  | 1989 | $433.40 |  
  | | 1990 | $423.80 |  | 1991 | $379.90 |  | 1992 | $356.30 |  | 1993 | $419.20 |  | 1994 | $409.80 |  | 1995 | $385.60 |  | 1996 | $367.80 |  | 1997 | $288.80 |  | 1998 | $288.00 |  | 1999 | $287.50 |  | 2000 | $272.15 |  | 2001 | $278.70 |  | 2002 | $346.70 |  | 2003 | $414.80 |  | 2004 | $438.10 |  | 2005 | $517.20 |  | 2006 | $636.30 |  | 2007 | $833.20 |  | 2008 | $950.00 |  
  |