CREATE TABLE "table1_14835826_1" (
  "series_num" real,
  "season_num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "original_air_date" text,
  "production_code" real,
  "u_s_viewers_millions" text
);

Question: How many series had 18.77 million viewers?
SQL: SELECT COUNT("series_num") FROM "table1_14835826_1" WHERE "u_s_viewers_millions"='18.77';