What's the lowest Year with a World Rank of 5th, with a Result greater than 20.31?
CREATE TABLE "200_meters" (
  "year" real,
  "result" real,
  "world_rank" text,
  "location" text,
  "date" text
);
SELECT MIN("year") FROM "200_meters" WHERE "world_rank"='5th' AND "result">20.31;