What is the minimum number of perfect 40s?
CREATE TABLE "average_scores_of_all_couples" (
  "rank_by_average" real,
  "place" text,
  "couple" text,
  "perfect_40s" real,
  "total" real,
  "number_of_dances" real,
  "season" real,
  "average" text
);
SELECT MIN("perfect_40s") FROM "average_scores_of_all_couples";