WASHINGTON (Reuters) - The U.S. unemployment rate unexpectedly fell in May and layoffs abated, the Labor Department said on Friday in a report that showed the latest signs the economic downturn caused by the COVID-19 pandemic was bottoming. The Labor Department's closely watched monthly employment report showed the jobless rate dropped to 13.3% last month from 14.7% in April. Nonfarm payrolls rose by 2.509 million jobs after a record plunge of 20.687 million in April.Economists polled by Reuters..