Air freight is the volume of freight, express, and diplomatic bags carried on each flight stage (operation of an aircraft from takeoff to its next landing), measured in metric tons times kilometers traveled.
About a quarter of the world drives on the left, and the countries that do are mostly old Britishcolonies. The following is a list of countries of the world and the side of the road the inhabitants drive on. Most of the people driving on the left side of the road use right-hand-drive vehicles and vice-versa.
The major ports and harbors selected on the basis of overall importance to each country. This is determined by evaluating a number of factors (e.g., dollar value of goods handled, gross tonnage, facilities, and military significance).
Total road network includes motorways, highways, and main or national roads, secondary or regional roads, and all other roads in a country. A motorway is a road designed and built for motor traffic that separates the traffic flowing in opposite directions."
International Road Federation, World Road Statistics and electronic files, except where noted.
Travel (% of service imports, BoP) covers goods and services acquired from an economy by travelers for their own use during visits of less than one year in that economy for either business or personal purposes. Services imports refer to economic output of intangible commodities that may be produced, transferred, and consumed at the same time. International transactions in services are defined by the International Monetary Fund's (IMF) Balance of Payments Manual (1993), but definitions may nevertheless vary among reporting economies."
International Monetary Fund, Balance of Payments Statistics Yearbook and data files.
Travel services (% of commercial service exports) covers goods and services acquired from an economy by travelers in that economy for their own use during visits of less than one year for business or personal purposes. Travel services include the goods and services consumed by travelers, such as lodging and meals and transport (within the economy visited).
Vehicles per populated land area Units: Vehicles/Populated LandArea (in km2) Units: Air pollution is generally greatest in densely populated areas. To take this into account, we used the Gridded Population of the World dataset available from CIESIN and calculated the total land area in each country inhabited with a population density of greater than 5 persons per sq. km. We then utilized this land area as the denominator for the vehicles data.
World Bank, World Development Indicators 2001, Washington, DC: World Bank, 2001