The economy of Russia has gradually transformed from a planned economy into a mixed market-oriented economy. It has enormous natural resources, particularly oil and natural gas. It is the world's ninth-largest economy by nominal GDP, and the sixth-largest by PPP. Russia's membership to the WTO was accepted in 2011. Russia's vast geography is an important determinant of its economic activity, with the country holding a large share of the world's natural resources. It has been widely described as an energy superpower; as it has the world's largest natural gas reserves, the second-largest coal reserves, the eighth-largest oil reserves, and the largest oil shale reserves in Europe. It is the world's leading natural gas exporter, the second-largest natural gas producer, and the second-largest oil exporter, and producer. Russia's foreign exchange reserves are the world's fourth-largest. It has a labour force of roughly 70 million people, which is the world's sixth-largest. Russia is the world's second-largest exporter of arms. Russia also has the world's fifth-largest number of billionaires. The oil and gas sector accounted up to roughly 40% of Russia's federal budget revenues, and up to 60% of its exports in 2019. In 2019, the Natural Resources and Environment Ministry estimated the value of natural resources to 60% of the country's GDP. Russia has one of the lowest external debts among major economies, although its inequality of household income and wealth remains comparatively high. Following the Russian invasion of Ukraine in 2022, the country has faced several sanctions and boycotts from the Western world and its allies, a move described as an "all-out economic and financial war" to isolate the Russian economy from the Western financial system. In spite of economic sanctions, Russia's economy remains quite resilient. History The Russian economy is volatile. Since 1989 its institutional environment was transformed from a socialist command economy to a capitalistic market system. Its industrial structure dramatically shifted away from heavy investment in manufacturing and agriculture toward market services, oil, gas, and mining. Richard Connolly argues that for the last four centuries, there are four main characteristics of the Russian economy that have shaped the system and persisted despite the political upheavals. First of all the weakness of the legal system means that impartial courts do not rule and contracts are problematic. Second is the underdevelopment of modern economic activities, with very basic peasant agriculture dominant into the 1930s. Third is technological underdevelopment, eased somewhat