Songs with minor-seventh chords peaked in the mid 1970s. Hmmm. I'm trying to think of examples. The '70s are a favorite of mine and I not a lot of tunes from them on my Spotify feed. How about you? Read more @ http://blogs.discovermagazine.com/d-brief/2015/05/06/music-last-50-years/#.VUtymKkutWw