Database: retail_complains
Question: What is the average number of complaints on credit cards filed by clients from New York in the 3 consecutive years starting from 2015?
SQL: SELECT CAST(COUNT(T2.`Complaint ID`) AS REAL) / 3 AS average FROM client AS T1 INNER JOIN events AS T2 ON T1.client_id = T2.Client_ID WHERE strftime('%Y', T2.`Date received`) BETWEEN '2015' AND '2017' AND T1.city = 'New York City' AND T2.Product = 'Credit card'