Igual hay que preguntárselo a Jagger que creo que ya había nacido por entonces.

No me queda otra que mostrarle un extracto del artículo de la Wikipedia sobre las décadas:

Although any period of ten years is a decade, a convenient and frequently referenced interval is based on the tens digit of the calendar year, as in using 1960s to represent the decade from 1960 to 1969. Often, for brevity, only the tens part is mentioned (60s or sixties), although this may leave it uncertain which century is meant. These references are frequently used to encapsulate pop culture or other widespread phenomena that dominated such a decade, as in The Great Depression of the 1930s.

http://en.wikipedia.org/wiki/Decade

Es una convención, asúmala, utilícela; y no desentone.