- Airports: Total number of airports. Runways must be useable, but may be unpaved. May not have facilities for refuelling, maintenance, or air traffic control.
- Airports > With paved runways > Total: Total number of airports with paved runways (concrete or asphalt surfaces)
- Commute > Distance: Distance. Based on 0-50 contributions for Argentina, Armenia, Austria and 63 more countries and 50-100 contributions for Australia, Brazil, Germany and 5 more countries and over 100 contributions for Canada, India, and United States. The surveys were conducted by numbeo.com from January, 2011 to February, 2014. See this sample survey for the United States, respondents were asked "Distance".
- Gross value added by transport, storage and communication: Gross Value Added by Kind of Economic Activity at current prices - US dollars.
- Gross value added by transport, storage and communication per capita: Gross Value Added by Kind of Economic Activity at current prices - US dollars. Figures expressed per capita for the same year.
- Inefficiency index: Each country's inefficiency rating in regards to traffic. Long commute times, poor traffic laws and other factors are taken into consideration.
- Rail > Railway length: Railway length in kilometers.
Road > Motor vehicles per 1000 people:
Motor vehicles per 1000 people.
No date was available from the Wikipedia article, so we used the date of retrieval.
- Road > Motorway density: Meters of motorway per square kilometer.
- Road > Motorway length: Total network length of all motorways in km.
- Road network length > Km: Length of road network in kilometers in European Union countries.
- Roads > Passenger cars > Per 1,000 people: Passenger cars (per 1,000 people). Passenger cars refer to road motor vehicles, other than two-wheelers, intended for the carriage of passengers and designed to seat no more than nine people (including the driver).
- Roads > Traffic index: Traffic Index is a composite index of time consumed in traffic due to job commute, estimation of time consumption dissatisfaction, CO2 consumption estimation in traffic and overall inefficiencies in the traffic system.
- Roadways > Unpaved: This entry gives the total length of the road network and includes the length of the paved and unpaved portions.
- Waterways: The total length and individual names of navigable rivers, canals, and other inland bodies of water.
SOURCES: CIA World Factbooks 18 December 2003 to 28 March 2011; traffic; United Nations Statistics Division; United Nations Statistics Division. Population figures from World Bank: (1) United Nations Population Division. World Population Prospects, (2) United Nations Statistical Division. Population and Vital Statistics Report (various years), (3) Census reports and other statistical publications from national statistical offices, (4) Eurostat: Demographic Statistics, (5) Secretariat of the Pacific Community: Statistics and Demography Programme, and (6) U.S. Census Bureau: International Database.; Numbeo traffic inefficiency index; Wikipedia: List of countries by rail transport network size (Long List); Wikipedia: List of countries by vehicles per capita; https://www.cia.gov/library/publications/the-world-factbook/fields/2085.html, Roadways.; International Road Federation, World Road Statistics and data files.
- Serbia ranked 18 places from the bottom for airports amongst Europe in 2013.