What series number is the episode entitled "Booty"?
CREATE TABLE "table1_28019988_2" (
  "series_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" text,
  "u_s_viewers_million" text
);
SELECT MAX("series_num") FROM "table1_28019988_2" WHERE "title"='\"Booty\"';