UPDATE 4-Romney releases more tax details, paid 14.1 pct in 2011
September 21, 2012 at 20:01 PM EDT
WASHINGTON, Sept 21 (Reuters) - Republican presidential candidate Mitt Romney fought back on Friday against Democrats' claims that he paid no taxes in some years, releasing a letter from his accountants saying he paid an effective federal tax rate of at least 13.6 percent annually over 20 years.
