Source:  MRO Global Outlook. Note: For many airlines the share of passenger and cargo revenue does not add to 100%, mainly because airlines have other sources of revenue such as real estate or aircraft maintenance services.
Passenger and Cargo Share of Operating Revenues, Selected Airlines, 2013
Most airlines derive revenues from both passenger and air cargo operations. This can take the form of a dedicated cargo branch operating cargo only planes to cargo carried in the bellyhold of passenger aircrafts on scheduled services. For North American airlines, the share of cargo in operating revenue is usually less than 5%. The main reason is that many airlines are mostly focusing on domestic services. Comparatively, European, Asian and Latin American airlines have a higher share of cargo revenue, in part because they are more focusing on long distance services that are more prone to include cargo. For instance, EVA Airways (Taiwan) and Korean Air have small domestic markets, so the majority of their services are international. So, cargo account for 29% and 24% of their revenues. Sill, two of the world's largest airlines, FedEx and UPS Airlines, are strictly focusing on cargo.