Which average Winner's share ($) has a Score of 281 (−7), and a Player of hale irwin, and a Year smaller than 1983?
CREATE TABLE "winners_and_honorees" (
  "year" real,
  "player" text,
  "country" text,
  "score" text,
  "margin_of_victory" text,
  "winner_s_share" real
);
SELECT AVG("winner_s_share") FROM "winners_and_honorees" WHERE "score"='281 (−7)' AND "player"='hale irwin' AND "year"<1983;