Tony Bennett, the singer Frank Sinatra called "the best in the business," is retiring from performing at the age of 95, after eight decades on stage and in clubs. Earlier this year it was announced he had Alzheimer's disease, diagnosed five years earlier; but he'd continued to perform. His last performance was just two weeks ago, with Lady Gaga, in sold-out shows at Radio City Music Hall in New York. He spoke with Terry Gross in 1982, 1991, and 1998.