RICHMOND, Va. (AP) _ Virginia’s unemployment rate remained at the lowest rate in three years in May and is still below the national average.    The Virginia Employment Commission says Virginia’s seasonally adjusted unemployment rate stayed at 5.6 percent in May. That’s 0.6 percentage points lower than a year ago. Virginia’s jobless rate has been trending down since January 2010, when joblessness peaked at 7.3 percent. Officials say nonfarm employment increased by 24,800 jobs in May. It was the fourth consecutive monthly increase. Virginia’s rate is still below the national average, which dropped to 8.2 percent in May. The Labor Department says unemployment rates fell in 14 states and the District of Columbia, increased in 18 states and remained flat in 18 states.