What is the highest value of PF when Ends Lost is 51?
CREATE TABLE "round_robin_standings" (
  "locale" text,
  "skip" text,
  "w" real,
  "l" real,
  "pf" real,
  "pa" real,
  "ends_won" real,
  "ends_lost" real,
  "blank_ends" real,
  "stolen_ends" real,
  "shot_pct" text
);
SELECT MAX("pf") FROM "round_robin_standings" WHERE "ends_lost"=51;