The widening gap between the rich getting richer while the majority have flat incomes or lose income causes unhappiness, U.S. researchers found. In 2010, the top 20 percent of Americans earned 49.4 percent of the nation's income, compared with the 3.4 percent earned by the some 15 percent of the population living below the poverty line, U.S. Census figures said. Psychologist Shigehiro Oishi and Selin Kesebir, both of the University of Virginia, and Ed Diener of the University of Illinois said in the last 40 years, "we've seen that people seem to be happier when there is more equality.&quo...