What is the average round in which a Safety with an overall rank higher than 89 was drafted?
CREATE TABLE "1997_new_england_patriots_draft_selectio" (
  "round" real,
  "overall" real,
  "player" text,
  "position" text,
  "college" text
);
SELECT AVG("round") FROM "1997_new_england_patriots_draft_selectio" WHERE "position"='safety' AND "overall">89;