What was the 18 to 49 rating when 9.50 million watched?
CREATE TABLE "u_s_nielsen_ratings" (
  "episode" real,
  "first_air_date" text,
  "rating_18_49" text,
  "share_18_49" real,
  "viewers_millions" text,
  "rank_timeslot" text,
  "rank_night" text
);
SELECT "rating_18_49" FROM "u_s_nielsen_ratings" WHERE "viewers_millions"='9.50';