How many episodes were watched by 12.72 million U.S. viewers?
CREATE TABLE table_72317 (
    "No. in series" real,
    "No. in season" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "U.S. viewers (millions)" text
)
SELECT COUNT("Written by") FROM table_72317 WHERE "U.S. viewers (millions)" = '12.72'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: How many episodes were watched by 12.72 million U.S. viewers? ### Input: CREATE TABLE table_72317 (
    "No. in series" real,
    "No. in season" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "U.S. viewers (millions)" text
) ### Response: SELECT COUNT("Written by") FROM table_72317 WHERE "U.S. viewers (millions)" = '12.72'