What was the archive for episode with 6.6 million viewers?
CREATE TABLE "table1_1601935_1" (
  "episode" text,
  "broadcast_date" text,
  "run_time" text,
  "viewers_in_millions" text,
  "archive" text
);
SELECT "archive" FROM "table1_1601935_1" WHERE "viewers_in_millions"='6.6';