He was elgible for all those years; he was subject to the draft all those years -- he just got a 2-S deferment!
But from what I remember, your lottery number was all-important then.
Maybe I'm wrong, but it looks like Edwards was only draft-eligible that one year, 1970, if he really did graduate from high school in 1969.
Other years he wouldn't have had to get deferments, or am I wrong here?