What time did the season finale air on May 20, 2003?
CREATE TABLE "u_s_television_ratings" (
  "season" text,
  "timeslot" text,
  "premiere" text,
  "finale" text,
  "tv_season" text,
  "ranking" text,
  "viewers_in_millions" real
);
SELECT "timeslot" FROM "u_s_television_ratings" WHERE "finale"='may 20, 2003';