Airline consumers have seen the cost of air travel grow steadily over the years with the increasing ancillary fees--or any charge that’s not airfare.

The top 10 earners made $20.4 billion in 2013, according to IdeaWorks, a consulting group which tracks such revenue.  Spirit Airlines and Wizz Air both  made more than a third of their money from ancillary sales, while Ryanair, often criticized for nickle and diming customers, made just under a quarter of its income from the practice.

And ten airlines in total raked in over $1 billion in ancillary revenue. 

United Airlines made $5.7 billion in non-ticket fees, American and US Airways made a combined $3.18 billion, Delta 2.52 and Lufthansa generated just over a billion.

While airlines commonly make money on such things as checked baggage,  in-flight WiFi, and premium seating, charges for services include frequent flier miles sold to partners, access to premier airport clubs, and commissions from car rentals.  

The latest numbers in the 2014 CarTrawler Yearbook of Ancillary Revenue, show a range of services.

Southwest realized $195 million during 2013 from its EarlyBird check in feature which allows earlier boarding-- and faster access to that much coveted overhead luggage space.

Delta expects SkyMiles revenue to bring $1.3 billion alone for 2014.

Despite the fact that airlines have raised prices to combat economic trouble, Norwegian made a surprising decision to donate 1 krone (about $0.17 USD) from each bottle of water sold onboard to UNICEF. In 2013, the airline donated $212,000 from the sale of 1.3 million bottles.