What is the average episode number where jimmy mulville was the 4th performer?
CREATE TABLE table_37275 (
    "Date" text,
    "Episode" real,
    "Performer 1" text,
    "Performer 2" text,
    "Performer 3" text,
    "Performer 4" text
)
SELECT AVG("Episode") FROM table_37275 WHERE "Performer 4" = 'jimmy mulville'
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: What is the average episode number where jimmy mulville was the 4th performer? ### Input: CREATE TABLE table_37275 (
    "Date" text,
    "Episode" real,
    "Performer 1" text,
    "Performer 2" text,
    "Performer 3" text,
    "Performer 4" text
) ### Response: SELECT AVG("Episode") FROM table_37275 WHERE "Performer 4" = 'jimmy mulville'