What's melbourne's average year?
CREATE TABLE table_51308 (
    "Player" text,
    "Team" text,
    "Opponent" text,
    "Year" real,
    "Score" text
)
SELECT AVG("Year") FROM table_51308 WHERE "Team" = 'melbourne'
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's melbourne's average year? ### Input: CREATE TABLE table_51308 (
    "Player" text,
    "Team" text,
    "Opponent" text,
    "Year" real,
    "Score" text
) ### Response: SELECT AVG("Year") FROM table_51308 WHERE "Team" = 'melbourne'