The number of international first- and business-class passengers in May grew by less than 2 percent year over year,

marking a third consecutive month of declining premium-market growth, according to the International Air Transport Association. International economy passenger counts in May grew by more than 5 percent year over year. "There may be a shift to cheaper seats by business travelers, or rather their corporate buyers," according to IATA. "However, the main reason for this deterioration in seat mix is the weakness of European markets."