It’s interesting that SW’s “glory days” lasted only three years.
As of May 24th, 1983, there were only two Star Wars films. So if you’re saying the “glory days” are the years in which only Star Wars and/or Empire existed, that’s six years (1977-1983). That’s if I understand your intent correctly. If you intended to say Empire sucked all the glory out of the franchise, then you just go right ahead saying three years.
I refer to SW & ESB as the “glory days”, so maybe it was six instead of three. What I probably meant was that it peaked after three years. It seems most hardcore SW fans only count the first two films of the franchise and nothing else; heck, TFA was literally built on elements solely from ANH & ESB.