On what date was the attendance greater than 18,118 when Colorado was the visitor?
CREATE TABLE "october" (
  "date" text,
  "visitor" text,
  "score" text,
  "home" text,
  "decision" text,
  "attendance" real,
  "record" text
);
SELECT "date" FROM "october" WHERE "attendance">'18,118' AND "visitor"='colorado';