user: ### NOW ANSWER:
Question: where value world rank is 12, what is the quantity world rank?
Columns: ['Rank', 'Commodity', 'Value (Int $1000)', 'Production (MT)', 'Quantity world rank', 'Value world rank']
Types: ['real', 'text', 'real', 'real', 'text', 'text']
Sample row: [1.0, 'Wheat', 939150.0, 6400000.0, '19', '17']
SQL:

assistant: SELECT "Quantity world rank" FROM "Table" WHERE "Value world rank" = '12';