It's almost a year since Westpac chief executive Gail Kelly announced that the bank was making a "tilt to growth", with a return to system growth in the Australian mortgage market.However, the latest Australian Prudential Regulation Authority banking statistics show that regaining lost market share is no easy task.According to APRA, banks' mortgage portfolios have grown by 6.3 per cent over the 12 months to April (according to the Reserve Bank the growth rate is 6.1 per cent). Westpac's book grew by five per cent over the same period - around 0.8 times system.Over the six months to April, Westpac's growth was around 0.9 times system - 2.9 per cent compared with system growth of 3.2 per cent. Over the three months to April the bank's mortgage book has continued to grow at a rate between 0.8 and 0.9 times system.Among other lenders, Macquarie Bank continues to report very high growth. Its mortgage portfolio grew by 7.5 per cent over the three months to April, compared with system growth of 1.6 per cent.Citibank and Bendigo and Adelaide Bank both grew by 3.4 per cent over the same period, Teachers Mutual Bank grew by three per cent, AMP Bank by 1.8 per cent, ANZ and NAB by 1.7 per cent.Among those that grew below system over the three months to April, Commonwealth Bank's mortgage portfolio grew by 1.4 per cent, ME Bank grew by 1.4 per cent, Suncorp by 0.9 per cent, ING Direct by 0.5 per cent and HSBC by 0.4 per cent.According to the latest Reserve Bank figures, loans to residential property investors were up 0.8 per cent in April and up 8.2 per cent over the 12 months to April.Loans to owner-occupiers were up 0.5 per cent in April and five per cent over the year.