Tell me the highest series # for september 22, 1976
CREATE TABLE "season_4_1976_1977" (
  "series_num" real,
  "season_num" real,
  "title" text,
  "original_air_date" text,
  "tape_date" text
);
SELECT MAX("series_num") FROM "season_4_1976_1977" WHERE "original_air_date"='september 22, 1976';