Database: financial
Question: Who are the account holder identification numbers whose who have transactions on the credit card with the amount is less than the average, in 1998?
SQL: SELECT T1.account_id FROM trans AS T1 INNER JOIN account AS T2 ON T1.account_id = T2.account_id WHERE STRFTIME('%Y', T1.date) = '1998' AND T1.operation = 'VYBER KARTOU' AND T1.amount < (SELECT AVG(amount) FROM trans WHERE STRFTIME('%Y', date) = '1998')