Which Social Democratic Party has a Green smaller than 0?
CREATE TABLE table_39090 (
    "Election" real,
    "Labour" real,
    "Conservative" real,
    "Liberal" real,
    "Social Democratic Party" real,
    "Social and Liberal Democrats/ Liberal Democrats" real,
    "Independent" real,
    "Green" real,
    "Other" text,
    "Control" text
)
SELECT AVG("Social Democratic Party") FROM table_39090 WHERE "Green" < '0'
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: Which Social Democratic Party has a Green smaller than 0? ### Input: CREATE TABLE table_39090 (
    "Election" real,
    "Labour" real,
    "Conservative" real,
    "Liberal" real,
    "Social Democratic Party" real,
    "Social and Liberal Democrats/ Liberal Democrats" real,
    "Independent" real,
    "Green" real,
    "Other" text,
    "Control" text
) ### Response: SELECT AVG("Social Democratic Party") FROM table_39090 WHERE "Green" < '0'