What's the highest attendance for a game the Texan's played at Arrowhead Stadium?
CREATE TABLE "preseason" (
  "week" text,
  "date" text,
  "opponent" text,
  "result" text,
  "game_site" text,
  "record" text,
  "attendance" real
);
SELECT MAX("attendance") FROM "preseason" WHERE "game_site"='arrowhead stadium';