Despite intense competitive activity around fixed mortgage rates this year, lenders have not had much success in stimulating lending activity.The latest Reserve Bank of Australia lending figures show month-on-month growth in owner-occupier mortgage balance has been unchanged at 0.4 per cent since February, while there has been no growth in investor mortgage balances since December.Overall, housing credit balances were up 0.3 per cent in April and 3.9 per cent over the 12 months to April. The annual growth rate is the lowest recorded in the RBA data series, which goes back to 1977.Personal credit balances continue to fall - down 0.3 per cent in April and down 2.8 per cent over 12 months.There was no growth in business credit balances in April and growth over the 12 months was just 4.5 per cent.According to APRA's latest monthly banking statistics, ANZ, Commonwealth Bank, NAB and Westpac are all running below system growth over the 12 months to April. ANZ's figures are particularly weak; the value of its mortgage book has fallen 0.9 per cent over the past year.The APRA figures show that ANZ's mortgage book has continued to fall steadily over the past few months. Balances were down 0.7 per cent over the three months to April and 0.2 per cent in April.Other lenders that suffered declines in April include Bank of Queensland, ING, NAB, Suncorp, G&C Mutual Bank, Police Bank, QPCU and Teachers Mutual Bank.Lenders growing above system over 12 months include Arab Bank, Auswide, Bank of Us, Bendigo and Adelaide Bank, HSBC Bank Australia (up 37.4 per cent over 12 months), ING, Bank of Sydney (up 35.4 per cent), Macquarie Bank (up 17 per cent) and ME Bank.