It gets worse and worse as we go forward. I was going to say 1985 because that's when I was in my 20s and when the best music happened. But they made the girl look horrible in that video. Everything after that is just trash. So I'll stick with 1975 when the classic rock bands were at their height, and people had moved on from the hippy stage.
All I know is that hats need to come back in style. Nobody wears hats day to day anymore, except maybe baseball caps, and those are just meh. Hats have been out of style my entire life, its kind of weird that for most of history before that they were pretty much the norm.