For each payment method, return how many customers use it.
SELECT payment_method_code ,  count(*) FROM customers GROUP BY payment_method_code
SELECT payment_method_code ,  count(*) FROM customers GROUP BY payment_method_code
[{'payment_method_code': 'Credit Card', 'count(*)': 10}, {'payment_method_code': 'Direct Debit', 'count(*)': 5}]