Earnings by foreign banks  are improving, but remain well below industry benchmarks.The return on equity for eight foreign bank subsidiaries lifted above 10 per cent in the December 2014 quarter, a return rarely achieved over the last four years.Australian Prudential Regulation Authority data shows foreign bank subsidiaries lifted profit on the back of a rise in non-interest income rather than through lower bad debt expenses.Among the bank competitors of foreign banks, mutual banks and credit union reported profits at two-thirds the ROE of foreign banks.