Passenger activity at Des Moines International Airport was up by 12.7 percent year-over-year in May, the Des Moines Airport Authority announced today. A total of 215,416 passengers passed through the airport last month, up from 191,126 during the same month a year ago. Year-to-date, passenger activity is up 5.7 percent. U.S. Airways led the way with a 46.8 percent increase year-over-year for the month of May, and Southwest Airlines had a 43.6 percent increase. Cargo activity at the airport was down 0.9 percent both for the month and year to date.