Federal Reserve Chairman Ben Bernanke said Tuesday that record levels of long-term unemployment will alter the U.S. job market for the worse for the foreseeable future. Bernanke said at a Senate Budget Committee hearing that the natural rate of unemployment -- or the level of unemployment that results when the economy is supporting as many jobs as it can -- has risen from about four percent in the early 2000s to more than five percent because so many Americans have been out of work for so long.