The U.S. economy added jobs at a slower pace in June than in May, suggesting that the slowdown in the economy might be longer-lasting and more severe than previously expected.Nonfarm payrolls rose by 18,000 in June, below consensus estimates for a 125,000 gain.Job gains in May were revised down to 25,000 in May from the initial estimate of 54,000.The unemployment rate rose to 9.2% in June from 9.1% in May, reaching the highest level since December. Economists had expected the unemployment rate to remain steady.