Airlines this year will collect $59.2 billion in ancillary revenue globally, an increase of 18.8 percent year over year,

according to a projection by research firm IdeaWorksCompany and car rental booking platform CarTrawler. Of that total, $36.7 billion will come from such services as checked baggage, premium seats and on-board dining, with the remainder generated from activities including selling frequent-flyer miles and commissions from car rentals, hotels and other travel services. Since the research project began in 2010, airlines' global ancillary revenue has increased 163 percent.