What is the highest Top-5 that has 18 or more events with a Top-25 of 23?
CREATE TABLE "summary" (
  "tournament" text,
  "wins" real,
  "top_5" real,
  "top_10" real,
  "top_25" real,
  "events" real,
  "cuts_made" real
);
SELECT MAX("top_5") FROM "summary" WHERE "events">18 AND "top_25"=23;