How many times did Saxby Chambliss have a lead margin of 21?
CREATE TABLE table_1524 (
    "Poll Source" text,
    "Dates administered" text,
    "Democrat: Jim Martin" text,
    "Republican: Saxby Chambliss" text,
    "Lead Margin" real
)
SELECT COUNT("Republican: Saxby Chambliss") FROM table_1524 WHERE "Lead Margin" = '21'
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: How many times did Saxby Chambliss have a lead margin of 21? ### Input: CREATE TABLE table_1524 (
    "Poll Source" text,
    "Dates administered" text,
    "Democrat: Jim Martin" text,
    "Republican: Saxby Chambliss" text,
    "Lead Margin" real
) ### Response: SELECT COUNT("Republican: Saxby Chambliss") FROM table_1524 WHERE "Lead Margin" = '21'