What was the distance (in miles) of the championship were the winning horse was Koona?
CREATE TABLE "world_championship_winners" (
  "year" real,
  "location" text,
  "distance_miles" real,
  "rider_names" text,
  "horse_name" text,
  "best_conditioned_horse" text
);
SELECT "distance_miles" FROM "world_championship_winners" WHERE "horse_name"='Koona';