Which is the lowest round to have a pick of 12 and position of linebacker?
CREATE TABLE "atlanta_falcons_draft_history" (
  "round" real,
  "pick_num" real,
  "overall" real,
  "name" text,
  "position" text,
  "college" text
);
SELECT MIN("round") FROM "atlanta_falcons_draft_history" WHERE "pick_num"=12 AND "position"='linebacker';