Passenger numbers were once again improved at Des Moines International Airport in May, as the airport reported a 5.8 percent year-over-year increase in the total number of passengers who boarded or exited planes in Des Moines. A total of 191,126 passengers went through in the month, up from 180,631 in the same month a year ago. A total of 884,320 passengers have gone through the airport this year, up 7.8 percent from the first five months of 2012.