How many points for maserati v12 engines in 1968?
CREATE TABLE "complete_world_championship_results" (
  "year" real,
  "entrant" text,
  "chassis" text,
  "engine" text,
  "points" real
);
SELECT COUNT("points") FROM "complete_world_championship_results" WHERE "engine"='maserati v12' AND "year"=1968;