What is the average round of the defensive back player with a pick # greater than 5 and an overall less than 152?
CREATE TABLE "atlanta_falcons_draft_history" (
  "round" real,
  "pick_num" real,
  "overall" real,
  "name" text,
  "position" text,
  "college" text
);
SELECT AVG("round") FROM "atlanta_falcons_draft_history" WHERE "pick_num">5 AND "position"='defensive back' AND "overall"<152;