The harder banks work at their retail customer satisfaction scores the less competitive advantage they get out of them. The latest Roy Morgan Research consumer banking customer satisfaction report, released yesterday, shows a 4.5 percentage point spread between the big four banks - the narrowest gap in a decade.Roy Morgan industry communications director Norman Morris said the gap between the big four 12 months ago was 6.7 percentage points and five years ago it was 13 percentage points.It is a similar story with the regionals. The gap in satisfaction ratings between Bendigo Bank, at the top of the table, and BankWest was almost 30 percentage points in 2002 and 2003 but the spread between top and bottom has narrowed to less than10 points now.ANZ retains its top ratings among the big banks, followed by Commonwealth Bank. After falling to the bottom of the table earlier this year Westpac has edged back ahead of National Australia Bank; the gap between them is only two basis points.ING Direct remains the highest rating bank overall, followed by Bendigo Bank, Suncorp and Bank of Queensland.Most banks have improved their customer satisfaction ratings this year, with Citibank showing the biggest increase. It is still the lowest-rating bank by some margin, however.Those that have lost ground since the start of the year include Westpac, Adelaide Bank, Bank of Queensland, St George, and HSBC.