What years did Birger Ruud win the FIS Nordic World Ski Championships?
CREATE TABLE table_21696 (
    "Winner" text,
    "Country" text,
    "Winter Olympics" text,
    "FIS Nordic World Ski Championships" text,
    "Holmenkollen" text
)
SELECT "FIS Nordic World Ski Championships" FROM table_21696 WHERE "Winner" = 'Birger Ruud'
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: What years did Birger Ruud win the FIS Nordic World Ski Championships? ### Input: CREATE TABLE table_21696 (
    "Winner" text,
    "Country" text,
    "Winter Olympics" text,
    "FIS Nordic World Ski Championships" text,
    "Holmenkollen" text
) ### Response: SELECT "FIS Nordic World Ski Championships" FROM table_21696 WHERE "Winner" = 'Birger Ruud'