U.S. airlines continue to report strengthening growth in the primary demand indicators, particularly on international routes, according to the Air Transport Association.

ATA says passenger revenue climbed by 21% year-on-year in May, the fifth consecutive month of growth. International revenue increased 36% and transpacific routes 51%.

“These results reflect encouraging signs of the nation’s economic recovery from the very deep hole of a year ago,” said ATA President James May. The ATA data cover seven major carriers and selected affiliates.

Passenger numbers rose 2% year-on-year and yield 17%. Yield growth in domestic and international markets has progressively strengthened in every month of this year. Domestic yield rose 14.1% in May, with transatlantic yield up 28.3%, Latin America 10.9% and transpacific 25.2%.

Meanwhile, cargo traffic jumped 17% year-on-year in April, with an 8% domestic gain and a 25% rise on international routes. Cargo data lag passenger numbers by a month.