Thought this was an interesting interview with the lead singer of Steam, Gary DeCarlo, where he briefly says (at 4:16 mark) that in 1969 when their song came out na na na na was popular in song lyrics because of "Hey Jude" and previously in Wilson Pickett's "Land of 1000 Dances". It was also mentioned on this video that when "Na na na na hey hey hey goodbye" was released it knocked The Beatles out of the No. 1 spot which they held for "Something." Maybe it was the na na na na in the song that did it
Gary DeCarlo died of cancer in 2017 at his home in Connecticut.
Love this live performance of DeCarlo singing "Hey Hey Hey Goodbye" https://www.youtube.com/watch?v=zbItRD40KJ0