WASHINGTON D.C. — President Barack Obama and his wife Michelle reported half a million dollars in income for 2013, down from the previous year as revenues from his best-selling books continued to fall, according to their tax returns released by the White House on Friday. The Obamas earned $503,183 last year and after deductions had an adjusted gross income of $481,098. They paid $98,169 in federal taxes, or 20.4 percent, and donated nearly $60,000 to charities, the documents showed.