Which polling institute showed a lead of 6%?
CREATE TABLE table_66677 (
    "Date(s) Released" text,
    "Polling institute" text,
    "Nationalist" text,
    "Labour" text,
    "Democratic Alternative" text,
    "Undecided/ No answer" text,
    "Lead" text
)
SELECT "Polling institute" FROM table_66677 WHERE "Lead" = '6%'
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 showed a lead of 6%? ### Input: CREATE TABLE table_66677 (
    "Date(s) Released" text,
    "Polling institute" text,
    "Nationalist" text,
    "Labour" text,
    "Democratic Alternative" text,
    "Undecided/ No answer" text,
    "Lead" text
) ### Response: SELECT "Polling institute" FROM table_66677 WHERE "Lead" = '6%'