Which polling institute has a 30.7% for social democratic?
CREATE TABLE table_name_81 (
    polling_institute VARCHAR,
    social_democratic VARCHAR
)
SELECT polling_institute FROM table_name_81 WHERE social_democratic = "30.7%"
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 polling institute has a 30.7% for social democratic? ### Input: CREATE TABLE table_name_81 (
    polling_institute VARCHAR,
    social_democratic VARCHAR
) ### Response: SELECT polling_institute FROM table_name_81 WHERE social_democratic = "30.7%"