The nation’s unemployment rate fell to 3.9 percent for the first time since 2000, with the economy gaining 164,000 jobs in April, according to data released Friday morning by the Department of Labor. Wage growth remained sluggish in April, with hourly pay inching up at a rate of only 2.6 percent. However, the slow-but-steady growth rate may still be enough to convince the Federal Reserve to keep raising rates to keep inflation in check.