1988. I looked at every game in KLOV by Taito for 1987, 1988 and 1989 and couldn't figure it out. KLOV is missing photo's of the majority of those games. I didn't look through arcadeflyers.com for it though, there was way too many to check, I was too lazy.
you might try PMing oregonarcade. He had one, ID'd what it was, and could probably tell you. I think it was Flying Hawk or one of those random scrolling shooters, I just can't remember off the top of my head what he said.