Among all the users with the average ratings of at least 4 and above of all reviews, calculate the percent that have no fans or followers.
average ratings of at least 4 refers to user_average_stars > = 4; no fans or followers refers to user_fans = 'None'; percentage = divide(count(user_id where user_average_stars > = 4 and user_fans = 'None'), sum(user_id where user_average_stars > = 4))*100%
SELECT CAST(SUM(CASE WHEN user_fans = 'None' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(user_id) FROM Users WHERE user_average_stars >= 4