According to the Barna Group, an evangelical polling firm, forty-seven per cent of Americans read the Bible every week. But other research has found that ninety-one per cent of American households own at least one Bible -- the average household owns four -- which means that Bible publishers manage to sell twenty-five million copies a year of a book that almost everybody already has.-- Daniel Radosh, in "The Good Book Business", The New Yorker, Dec. 18 2006.