ShowbizUS chat show legend diesMetro11 April 2012Johnny Carson, the legendary American chat show king, died yesterday of emphysema aged 79.Carson hosted NBC's popular The Tonight Show for 30 years, drawing in an estimated 12million viewers a night, until he was replaced in 1992 by Jay Leno.'He was surrounded by his family, whose loss will be immeasurable,' said his nephew Jeff Sotzing.MORE ABOUTJay LenoNbc