The value of credit card balances accruing interest has fallen to its lowest level since December 2009.According to the latest Reserve Bank credit and charge card data, balances accruing interest on credit and charge card accounts fell from A$34.4 billion in July to $33.5 billion in July.That is $2155 for each of the 15.6 million credit and charge accounts currently operating.Consumers made 163.3 million purchases on their credit and charge accounts in August (an average of 10.5 purchases per account) - down from 173.7 million in July.The value of purchases was $22.3 billion (an average of $1433 per account) - down from $23.4 billion in July.The value of purchases on debit cards rose from $17.7 billion (an average of $456 per card) to $17.9 billion over the same period.Over the 12 months to August, the average monthly spend per credit and charge card account has increased from $1415 to $1433, while the average monthly spend per debit account has increased from $454 to $456.MWE Consulting principal Mike Ebstein said that, although recent results have been patchy, the long-term outlook indicates a positive trend in average spend per account.