How many were the shares when the viewers reached 3.11 million?
CREATE TABLE "u_s_nielsen_ratings" (
  "episode_number" real,
  "episode" text,
  "rating" text,
  "share" real,
  "rating_share_18_49" text,
  "viewers_millions" text,
  "rank_overall" text
);
SELECT COUNT("share") FROM "u_s_nielsen_ratings" WHERE "viewers_millions"='3.11';