How many millions of U.S viewers are there when the director is andy wolk?
CREATE TABLE table_31324 (
    "Series #" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "Production code" text,
    "U.S. viewers (million)" text
)
SELECT "U.S. viewers (million)" FROM table_31324 WHERE "Directed by" = 'Andy Wolk'
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 millions of U.S viewers are there when the director is andy wolk? ### Input: CREATE TABLE table_31324 (
    "Series #" real,
    "Title" text,
    "Directed by" text,
    "Written by" text,
    "Original air date" text,
    "Production code" text,
    "U.S. viewers (million)" text
) ### Response: SELECT "U.S. viewers (million)" FROM table_31324 WHERE "Directed by" = 'Andy Wolk'