World economy
The world economy or the global economy is the economy of all humans of the world, referring to the global economic system which includes all economic activities which are conducted both within and between nations, including production, consumption, economic management, work in general, exchange of financial values and trade of goods and services. In some contexts, the two terms are distinct "international" or "global economy" being measured separately and distinguished from national economies while the "world economy" is simply an aggregate of the separate countries' measurements. Beyond the minimum standard concerning value in production, use and exchange, the  definitions, representations, models and valuations of the world economy vary widely. It is inseparable from the geography and ecology of planet Earth. It is common to limit questions of the world economy exclusively to human economic activity and the world economy is typically judged in monetary terms, even in cases in which there is no efficient market to help valuate certain goods or services, or in cases in which a lack of independent research, genuine data or government cooperation makes establishing figures difficult. Typical examples are illegal drugs and other black market goods, which by any standard are a part  of the world economy, but for which there is by definition no legal market of any kind. However, even in cases in which there is a clear and efficient market to establish a monetary value, economists do not typically use the current or official exchange rate to translate the monetary units of this market into a single unit for the world economy since exchange rates typically do not closely reflect worldwide value, for example in cases where the volume or price of transactions is closely regulated by the government. Rather, market valuations in a local currency are typically translated to  a single monetary unit using the idea of purchasing power. This is the method used below, which is used for estimating worldwide economic activity in terms of real United States dollars or euros. However, the world economy can be evaluated and expressed in many more ways. It is unclear, for example, how many of the world's 7.8 billion people () have most of their economic activity reflected in these valuations. According to Maddison, until the middle of 19th century, global output was dominated by China and India. Waves of Industrial Revolution in Western Europe and Northern America shifted the shares  to the Western Hemisphere. As of 2022, the following 18 countries or collectives have reached an economy of at least US$2 trillion by GDP in nominal or PPP terms: Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, South Korea, Mexico, Russia, Saudi Arabia, Spain, Turkey, the United Kingdom, the United States and the European Union. Despite high levels of government investment, the World Bank predicted that the global economy would decrease by 5.2 percent in 2020. Cities account for 80% of global GDP, thus they would face the brunt of this decline. Statistical indicators. Communications. Telephones – main lines  in use: 843,923,500 (2007)4,263,367,600 (2008) Transport. Transportation infrastructure worldwide includes: Science, research and development. The Royal Society in a 2011 report stated that in terms of number of papers the share of English-language scientific research papers the United States was first followed by China, the UK, Germany, Japan, France, and Canada. In 2015, research and development constituted an average 2.2% of the global GDP according to the UNESCO Institute for Statistics. Metrics and rankings of innovation include the Bloomberg Innovation Index, the Global Innovation Index and the share of Nobel laureates per capita. From the scientific perspective, economic activities  are embedded in a web of dynamic, interrelated, and interdependent activities that constitute the natural system of Earth. Novel application of cybernetics in decision-making (such as in decision-making related to process- and product-design and related laws) and direction of human activity (such as economic activity) may make it easier to control modern ecological problems. Historical development. One example for a comparable metric other than GDP are the OECD Better Life Index rankings for different aggregative domains. The index includes 11 comparable "dimensions" of well-being: Economic studies. To promote exports, many government agencies publish on the web  economic studies by sector and country. Among these agencies include the USCS (US DoC) and FAS (USDA) in the United States, the EDC and AAFC in Canada, Ubifrance in France, the UKTI in the United Kingdom, the HKTDC and JETRO in Asia, Austrade and the NZTE in Oceania. Through Partnership Agreements, the Federation of International Trade Associations publishes studies from several of these agencies (USCS, FAS, AAFC, UKTI, and HKTDC) as well as other non-governmental organizations on its website globaltrade.net. See also. Regional economies: Events: Lists: