What is the sum of winners when 1983 is the years won?
CREATE TABLE "performance_in_uefa_super_cup_by_club" (
  "team" text,
  "winners" real,
  "runners_up" real,
  "years_won" text,
  "years_runners_up" text
);
SELECT COUNT("winners") FROM "performance_in_uefa_super_cup_by_club" WHERE "years_won"='1983';