DS9 ran till '99, though.

The first seasons were 30 years ago, but the ending is only about 25 years ago.

BSG, though, finished in 1979. If someone says "thirty years ago" and your first thought is the 70s, you might be old. BSG ended 45 years ago. It's 20 years older than the finale of DS9.

Edit: if someone asks you "who was president 30 years ago", do you instantly think of Jimmy Carter? Because BSG came out basically in the middle of his presidency. If your first thought was Bush or Reagan, you associate the Sci Fi of 30 years ago with reruns of BSG.