Leadbottom: What exactly are you measuring on the y-axis when you plot revivals? Industry awards, Top 40-100 charts, sales… music you like? What's the maths?

There were three Billboard Top 40 chart categories for North America; Folk wasn't one of them and neither were the 1930s. The Weavers and Belafonte charted as Pop artists. The Battle of New Orleans was Country. The First Time Ever I Saw Your Face was Pop or Country or R&B, depending on the artist.

One suspects if we add in all the stuff not mentioned or liked (The Tarriers, Arlo Guthrie, Steve Goodman, Neil Young &c &c &c) the thirty year peaks are in your consumer preferences.

PS: Dylan's revival 'backup' band (aka: The Traveling Wilburys) were all platinum recording artists in their own right many times over. That's a built-in base of several hundred million consumers for starters.