I maintain that what we think of as our musical decades really start at year 4. The 50s are 1954 (Elvis) through 1963. The 60s are 1964 (Beatles) through 1973. The 70s are 1974 (KISS) through 1983. The '80s are 1984 (Bon Jovi) through 1990. Only by the '90s, 1991 (Nirvana) through 2000, is it reset.