I don't see anything that disqualifies it from being in the 70s-- but then, I don't remember anything saying that it is in the 70s (though it was a couple of weeks ago that I watched the beginning).
The first subtitle says 1975 in the first episode.
The scenes in the office, while the guy is running away, looked like today. The elevator buttons. The ceiling tiles. Just looked modern. Though, they did feature a typewriter in one shot. A non electric one... which would be an odd feature in an office in 1975. I would think an electric one would be more appropriate.