What is the average pots of Alfa Romeo v12 after 1983?
CREATE TABLE "complete_formula_one_results" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "pts" real
);
SELECT AVG("pts") FROM "complete_formula_one_results" WHERE "engine"='alfa romeo v12' AND "year">1983;