what is the number of the episode in the season that had 7.19 millions of north american viewers? 
CREATE TABLE "table1_27914606_1" (
  "series_num" real,
  "season_num" real,
  "title" text,
  "written_by" text,
  "original_air_date" text,
  "u_s_viewers_millions" text
);
SELECT "season_num" FROM "table1_27914606_1" WHERE "u_s_viewers_millions"='7.19';