What is the maximum number of AFC championships?
CREATE TABLE "total_playoff_berths_while_in_the_afl_af" (
  "team" text,
  "division_titles" real,
  "playoff_berths" real,
  "afl_titles" real,
  "afc_championships" real,
  "super_bowl_championships" real
);
SELECT MAX("afc_championships") FROM "total_playoff_berths_while_in_the_afl_af";