What's the highest grid of Ronnie Bremer, who had more than 18 points?
CREATE TABLE "race" (
  "driver" text,
  "team" text,
  "laps" real,
  "time_retired" text,
  "grid" real,
  "points" real
);
SELECT MAX("grid") FROM "race" WHERE "driver"='ronnie bremer' AND "points">18;