"Decades" are (mostly) a marketing concept used to repackage and sell music from previous eras. The so-called "fifties," "sixties," and "seventies," as well as all the others are more full of diversity than any one defining style. Time and events don't really fit into neatly packaged blocks, beginning with a given year and ending with another. Any "decade" you care to look at will contain a variety of musical styles and genres. The "sixties" were not all "peace, love, dove" any more than the seventies were all about disco. Even if you narrow the scope of your queston to a single year, you will still have a diversity of country, classical, "pop," jazz, folk, ethnic, etc. All of these forms of music and many more are, at their best, all constantly evolving and offering something different than whatever came before. When you attempt to label a group of years as a "decade," you are limiting yourself and placing a false construct on something that by nature, resists such false limitations.