Calculate the percentage of business with attribute name of "Accepts Credit Cards".
percentage refers to DIVIDE(COUNT(attribute_name = 'Accepts Credit Cards'), COUNT(business_id))*100%
SELECT CAST(SUM(CASE WHEN T1.attribute_name = 'Accepts Credit Cards' THEN 1 ELSE 0 END) AS REAL) * 100 / COUNT(T1.attribute_name) FROM Attributes AS T1 INNER JOIN Business_Attributes AS T2 ON T1.attribute_id = T2.attribute_id