First, some additions:
1985
Agent Steel - "Skeptics Apocalypse"
Helloween - "Walls Of Jericho"
Ok, both of them were originally called speed metal, so one could argue whether they should be included here or not.
1986
Détente - "Recognize No Autority"
Original Sin - "Sin Will Find You Out"
Sacrilege - "Behind The Realms Of Madness"
1987
Mekong Delta - "Mekong Delta"
Hades - "Resisting Success"
Sacrilege - "Within The Prophecy"
1988
Anacrusis - "Suffering Hour"
Assassin - "Interstellar Experience"
Erosion - "Mortal Agony"
Mekong Delta - "The Music Of Erich Zann"
Sieges Even - "Life Cycle"
Znowhite - "Act Of God"
1989
Mekong Delta - "The Principle Of Doubt"
Mordred - "Fool's Game"
Powermad - "Absolute Power"
Watchtower - "Control And Resistance"
1990
Anacrusis - "Reason"
Hexenhaus - "The Edge Of Eternity"
Mekong Delta - "Dances Of Death"
Holy Moses - "World Chaos"
Well, it's nearly impossible for me to decide between 1986, 1987 and 1988, but since three of my alltime faves - "Suffering Hour", "A Tribute To Insanity" and "Act Of God" - were all released in 1988, I'll vote for the latter.