When the pos equals 18 what is the max amount of points?
CREATE TABLE "race_results" (
  "pos" real,
  "no" real,
  "driver" text,
  "team" text,
  "chassis_engine" text,
  "laps" real,
  "time_retired" text,
  "grid" real,
  "laps_led" real,
  "points" real
);
SELECT MAX("points") FROM "race_results" WHERE "pos"=18;