What is the year of the season that was 12?
CREATE TABLE "u_s_broadcast_and_ratings" (
  "season" real,
  "timeslot_et" text,
  "season_premiere" text,
  "season_finale" text,
  "tv_season" text,
  "rank" text,
  "viewers_millions" text
);
SELECT "tv_season" FROM "u_s_broadcast_and_ratings" WHERE "season"=12;