CREATE TABLE "list_of_players" (
  "position" text,
  "appearances" real,
  "goals" real,
  "first_appearance" real,
  "last_appearance" real
);

Question: What is the average goals when the last appearance was before 1984, there were more than 17 appearances, the first appearance was before 1961 and the position was mf?
SQL: SELECT AVG("goals") FROM "list_of_players" WHERE "last_appearance"<1984 AND "appearances">17 AND "first_appearance"<1961 AND "position"='mf';