How many millions of viewers are listed where the writer is Matthew Okumura?
CREATE TABLE "table1_2866503_1" (
  "no" real,
  "num" real,
  "title" text,
  "directed_by" text,
  "written_by" text,
  "u_s_air_date" text,
  "production_code" real,
  "u_s_viewers_million" text
);
SELECT "u_s_viewers_million" FROM "table1_2866503_1" WHERE "written_by"='Matthew Okumura';