How many values are in the PF cell when Jennifer Jones is skip?
CREATE TABLE table_21217 (
    "Province" text,
    "Skip" text,
    "W" real,
    "L" real,
    "PF" real,
    "PA" real,
    "Ends Won" real,
    "Ends Lost" real,
    "Blank Ends" real,
    "Stolen Ends" real,
    "Shot Pct." real
)
SELECT COUNT("PF") FROM table_21217 WHERE "Skip" = 'Jennifer Jones'
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 values are in the PF cell when Jennifer Jones is skip? ### Input: CREATE TABLE table_21217 (
    "Province" text,
    "Skip" text,
    "W" real,
    "L" real,
    "PF" real,
    "PA" real,
    "Ends Won" real,
    "Ends Lost" real,
    "Blank Ends" real,
    "Stolen Ends" real,
    "Shot Pct." real
) ### Response: SELECT COUNT("PF") FROM table_21217 WHERE "Skip" = 'Jennifer Jones'