Big banks have restricted the rate of growth in the balance sheets of their Australian businesses over the first six months of 2011, monthly banking statistics published by the Australian Prudential Regulation Authority show.In all key product categories, the major banks have reported muted growth that is below market, and, in some cases, negative growth.The decline in retail deposits across the banking system is emphasised by the experience of the two largest banks that dominate the supply of household credit.As the table shows, the retail deposit books of Commonwealth Bank and Westpac have declined over six months.A handful of smaller banks, including RaboDirect and ME Bank, show the strongest growth.The bank-level data on deposit flows also shows strong growth for HSBC over six months, though shorter term data shows an outflow from HSBC over the last three months.In home loans, three of the big banks (with NAB as the exception) are growing at below system.In business lending, foreign banks have stepped up their level of lending in a segment with uneven levels of growth (and, as reported above, negative growth over the last month).In business deposits, growth is scattered among smaller institutions, with the patterns of growth inconsistent.Two banks featured in the table based on six-month growth rates - Bank of Queensland and Citi - reported deposit outflows in June.