CREATE TABLE "atlanta_falcons_draft_history" (
  "round" real,
  "pick_num" real,
  "overall" real,
  "name" text,
  "position" text,
  "college" text
);

Question: What round on average was a defensive tackle selected?
SQL: SELECT AVG("round") FROM "atlanta_falcons_draft_history" WHERE "position"='defensive tackle';