what is the round when the pick # is less than 236 and the position is offensive guard?
CREATE TABLE "nfl_draft" (
  "round" real,
  "pick_num" real,
  "player" text,
  "position" text,
  "college" text
);
SELECT AVG("round") FROM "nfl_draft" WHERE "pick_num"<236 AND "position"='offensive guard';