In reviews of product with 5 stars, what is the percentage of the reviews coming from the division of East North Central?
5 stars refers to Stars = 5; percentage = divide(count(division = 'East North Central', count(division)) * 100%
SELECT CAST(SUM(CASE WHEN T1.division = 'East North Central' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T1.division) FROM district AS T1 INNER JOIN reviews AS T2 ON T1.district_id = T2.district_id WHERE T2.Stars = 5