How many people travel each year?

According to the Air Transport Action Group, the world's airlines carried a total of over 3 billion passengers in 2013. The International Air Transport Association has the 2012 figure as 2.8 billion. Oxford Economics projects significant growth in aviation through 2030, with passenger numbers expected to reach 5.9 billion.

Data from the World Bank shows that rail travel also remains a popular option. Traveling by train is especially common in India, China, Japan and Russia. The World Travel Association states that, as of 2014, France, Spain, the United States, Italy and China are the five most visited countries in the world.