CREATE TABLE "round_18" (
  "home_team" text,
  "home_team_score" text,
  "away_team" text,
  "away_team_score" text,
  "venue" text,
  "crowd" real,
  "date" text
);

Question: What date was Richmond the away team?
SQL: SELECT "date" FROM "round_18" WHERE "away_team"='richmond';