How many average points did the team Minardi Team USA have when there was a grid 3 and more laps than 68?
CREATE TABLE "race" (
  "driver" text,
  "team" text,
  "laps" real,
  "time_retired" text,
  "grid" real,
  "points" real
);
SELECT AVG("points") FROM "race" WHERE "team"='minardi team usa' AND "grid"=3 AND "laps">68;