Back to the 80s! Below are the winners for each year, followed by their credited songwriters and recording artist in parentheses. If no parentheses, then songwriter(s)/artist(s) are one and the same. People might nitpick about the technicality in one winner, but I'm going by Wikipedia.
1980 - "What a Fool Believes" - Kenny Loggins & Michael McDonald (The Doobie Brothers)
1981 - "Sailing" - Christopher Cross
1982 - "Bette Davis Eyes" - Donna Weiss & Jackie DeShannon (Kim Carnes)
1983 - "Always On My Mind" - Johnny Christopher, Mark James, & Wayne Carson (Willie Nelson)
1984 - "Every Breath You Take" - Sting (The Police)
1985 - "What's Love Got to Do with It" - Graham Lyle & Terry Britten (Tina Turner)
1986 - "We Are The World" - Michael Jackson & Lionel Richie (USA For Africa)
1987 - "That's What Friends Are For" - Burt Bacharach & Carole Bayer Sager (Dionne Warwick & Friends)
1988 - "Somewhere Out There" - James Horner, Barry Mann & Cynthia Weil (Linda Ronstadt & James Ingram)
1989 - "Don't Worry, Be Happy" - Bobby McFerrin
Looking at these, I'm going to bet 500 Internet imaginary dollars and say I think I know who's going to win this one, overplayed as it is on classic rock stations. Color me surprised if its actually outvoted. But I won't post that music video. Instead I'll post the parody that Sting recorded for SPITTING IMAGE back in the day.