I call EVERY TIME! The police in our local area now know enough to not go into the big questionairre about whether this is a domestic issue (they always assumed we were in a fight and I was just trying to "get him"). They have never caught him, unfortunately, but I always call and I just figure if I saw someone in traffic in front of me swerving, I would call and that's not even a known drunk.
I couldn't live with myself if someone were hurt or injured and I hadn't done whatever I could to stop it from happening. I hate that it's part of my reality, but that's not the issue.
Not fun, though, yes?