which country is the only one to have only one record holder for pole vaulting ?
CREATE TABLE table_204_678 (
    id number,
    "record" text,
    "athlete" text,
    "nation" text,
    "venue" text,
    "date" text,
    "#" number
)
SELECT "nation" FROM table_204_678 GROUP BY "nation" HAVING COUNT(*) = 1
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 country is the only one to have only one record holder for pole vaulting ? ### Input: CREATE TABLE table_204_678 (
    id number,
    "record" text,
    "athlete" text,
    "nation" text,
    "venue" text,
    "date" text,
    "#" number
) ### Response: SELECT "nation" FROM table_204_678 GROUP BY "nation" HAVING COUNT(*) = 1