Among the customers not subscribed to the mailing list, what percentage has given three or more stars in a review?
not subscribed to the mailing list refers to SubscribedToEmailList = 'FALSE'; percentage = MULTIPLY(DIVIDE(SUM(CustomerID WHERE StarRating > 3), COUNT(CustomerID) WHERE SubscribedToEmailList = 'FALSE'), 1.0);
SELECT CAST(COUNT(CASE WHEN T2.StarRating > 3 THEN 1 ELSE NULL END) AS REAL) * 100 / COUNT(T2.CustomerID) FROM customers AS T1 INNER JOIN rootbeerreview AS T2 ON T1.CustomerID = T2.CustomerID WHERE T1.SubscribedToEmailList = 'FALSE'