Letter Rate 29¢ Package Rate 29¢ Postcard Rate 19¢ Effective 2/3/1991 Great Britain 6/21/1993 Andrew Wiles Proves Last Theorem of Pierre de Fermat Andrew Wiles proved the last theorem of French mathematician Pierre de Fermat. He presented his proof to the public at a conference in Cambridge. A flaw was later discovered and the final proof was presented in May 1995. American President Bill Clinton (1/20/1993-1/20/2001) British Prime Minister John Major (11/28/1990-5/2/1997) German President Richard von Weizsäcker (7/1/1984-6/30/1994)