Better service standards are all very well, but customer satisfaction appears to be all about interest rates. The latest Roy Morgan Research consumer banking customer satisfaction research shows that the improved ratings of the big banks in 2013 were driven by home loan customers enjoying the banks' low rates.At the same time, term deposit customers reported lower satisfaction.Over the 12 months to December, the satisfaction rating of the Big Four banks increased by an average of 1.7 percentage points. Home-loan customer satisfaction rose by an average of 5.9 percentage points, while term deposit customers' ratings fell by an average of 0.9 points.Roy Morgan's industry communications director, Norman Morris, said increased use of internet banking was also a contributor to higher satisfaction levels. Morris said: "Internet banking is now used by 58.7 per cent of customers in an average four-week period, compared with only 33.9 per cent using branches. Internet banking satisfaction levels are high."Among the big banks, Commonwealth Bank had the highest satisfaction rating in December, with a score of 81.8 per cent, followed by National Australia Bank (80 per cent), Westpac (78.8 per cent) and ANZ (77.7 per cent).