user: Question: When 21 is the number of assists how many sets of blocks are there?
Columns: ['Player', 'Minutes', 'Field Goals', 'Rebounds', 'Assists', 'Steals', 'Blocks', 'Points']
Types: ['text', 'real', 'real', 'real', 'real', 'real', 'real', 'real']
Sample row: ['Sheri Sam', 1100.0, 180.0, 137.0, 88.0, 55.0, 8.0, 444.0]
SQL:

assistant: SELECT COUNT("Blocks") FROM "Table" WHERE "Assists" = 21.0;