Jelaskan 1980-an dari List of years in sumo

1989 in sumo Chiyonofuji and Hokutoumi vie for dominance at three and two championships respectively, Konishiki gets first tournament win

1988 in sumo Asahifuji has first win, Chiyonofuji takes the last four tournaments and record for longest bout winning streak in modern sumo history - later surpassed by Hakuho

1987 in sumo - Hokutoumi and Onokuni are promoted to yokozuna; Futahaguro is forced to retire