The nation’s employers stepped up their hiring in May, adding a robust 339,000 jobs, well above expectations and evidence of enduring strength in an economy that the Federal Reserve is desperately trying to cool. Friday's report from the government reflected the job market's resilience after more than a year of aggressive interest rate increases by the Fed. Notably, the unemployment rate rose to 3.7%, from a five-decade low of 3.4% in April.