Consumers continue to whittle away at their credit card balances and are also spending less on credit cards.According to the latest Reserve Bank payment data, the average balance accruing interest on Australia's 16.6 million credit card accounts in July was A$1941.42 per account  - down from an average of $1992.32 the previous month and $2000.25 in July last year.The total value of balances accruing interest on credit cards in July was $32.2 billion, compared with $32.9 billion the previous month and $32.2 billion in July last year.Consumers made purchases worth a total of $23.6 billion on credit and charge cards in July, compared with $25.5 billion in June and $24.7 billion in July last year.The average spend per card was $1421.79 in July, compared with $1540.48 in June and $1532.39 in July last year.One area of the credit and charge card market that is growing is card account numbers, which grew 2.8 per cent to 16.6 million over the 12 months to July.Spending on debit cards picked up month on month but has been steady over the past 12 months.The average value of purchases on debit cards in July was $483.55 per account, compared with $459.31 in June and $485.18 in July last year.The total value of debit card purchases in July was $20.9 billion.