What is the percentage of female customers who subscribed to the email list?
percentage = MULTIPLY(DIVIDE(COUNT(CustomerID WHERE Gender = 'F'), COUNT(CustomerID) WHERE SubscribedToEmailList = 'TRUE'), 1.0); female refers to Gender = 'F'; subscribed to the email list refers to SubscribedToEmailList = 'TRUE';
SELECT CAST(COUNT(CASE WHEN Gender = 'F' THEN 1 ELSE NULL END) AS REAL) * 100 / COUNT(SubscribedToEmailList) FROM customers WHERE SubscribedToEmailList = 'TRUE'