History of the expansion of the copyright term

From Charlie Nesson's IP PPT in Cyber One Class, Harvard Law School, Fall 2008 NEEDS TO BE MADE MORE ACCURATE

1790 14 years (maybe x2) 1831 42 years 1909 56 years 1962 59 years 1965 61 years 1967 63 years 1968 64 years 1970 66 years 1971 67 years 1972 68 years 1974 70 years 1976 75 years 1998 95 years