Bucks, Montgomery and Chester Counties are still below the national unemployment rate of a little over 9 percent. The U.S. Labor Department’s Bureau of Labor Statistics released the March numbers Wednesday.  Bucks County’s rate is 7.5 percent, Montgomery County’s rate is 6.9 percent, and Chester County has the lowest rate in Southeastern Pennsylvania at 6.2 percent.  All three counties improved from a year earlier, but they did not recover to the rates they had in March of 2009.