Credit card issuers have been watching account balances fall for most of the year and the trend continued in September. Reserve Bank figures released yesterday show that credit and charge card balances that are accruing interest have fallen to their lowest level since 2010.In September, total balances accruing interest stood at A$35 billion - down from $35.7 billion in August, and down from the year's high of $37.1 billion in April.Card account numbers have increased during the year - up from 14.9 million last December to 15.1 million in September. The average balance accruing interest has fallen from $2368 per account at the end of last year to $2319 per account in September.The value of credit card purchases fell from $21.6 billion in September to $19.5 billion in August.