Which letter was added to the name of "The Rolling Stones" in 1963?

Explanation

The Rolling Stones is an English rock band formed in 1960 by Mick Jagger (vocal) and Keith Richards (guitar). In 1969 "The Stones" was introduced as "the biggest rock and roll band in the world". The band named itself "Rollin' Stone" after the Muddy Waters' song by the same name, and in 1963 the 'g' was added. "Aftermath" (1966) was the first album solely created by the band. The song "Start Me Up" is played at NFL matches.