What is the evening gown number when the average is more than 8.984 in Louisiana and the preliminary is more than 8.597?
CREATE TABLE "final_competition_score" (
  "country" text,
  "preliminary" real,
  "interview" real,
  "swimsuit" real,
  "evening_gown" real,
  "average" real
);
SELECT COUNT("evening_gown") FROM "final_competition_score" WHERE "average">8.984 AND "country"='louisiana' AND "preliminary">8.597;