Soviet arms industry and high-tech research, though heavy industry still had an outsided influence. The Soviet government invested in hydroelectric and nuclear power projects to cater to the energy demand that the development carried. On 26 April 1986, however, a reactor in the Chernobyl Nuclear Power Plant exploded, resulting in the Chernobyl disaster, the worst nuclear reactor accident in history. Independence Mikhail Gorbachev pursued a policy of limited liberalization of public life, known as perestroika, and attempted to reform a stagnating economy. The latter failed, but the democratization of the Soviet Union fuelled nationalist and separatist tendencies among the ethnic minorities, including Ukrainians. As part of the so-called parade of sovereignties, on 16 July 1990, the newly elected Supreme Soviet of the Ukrainian Soviet Socialist Republic adopted the Declaration of State Sovereignty of Ukraine; after a putsch of some Communist leaders in Moscow failed to depose Gorbachov, outright independence was proclaimed on 24 August 1991 and approved by 92% of the Ukrainian electorate in a referendum on 1 December. Ukraine's new President, Leonid Kravchuk, went on to sign the Belavezha Accords and made Ukraine a founding member of the much looser Commonwealth of Independent States (CIS), though Ukraine never became a full member of the latter as it did not ratify the agreement founding CIS. These documents sealed the fate of the Soviet Union, which formally voted itself out of existence on 26 December. Ukraine was initially viewed as having favourable economic conditions in comparison to the other regions of the Soviet Union, though it was one of the poorer Soviet republics by the end of the Soviet Union. However, during its transition to the market economy, the country experienced deeper economic slowdown than almost all of the other former Soviet Republics. During the recession, between 1991 and 1999, Ukraine lost 60% of its GDP and suffered from hyperinflation that peaked at 10,000% in 1993. The situation only stabilized well after the new currency, the hryvnia, fell sharply in late 1998 partially as a fallout from the Russian debt default earlier that year. The legacy of the economic policies of the nineties was the mass privatization of state property that created a class of extremely powerful and rich individuals known as the oligarchs. The country would then fall into sharp recessions as a result of the 2008 global financial crisis, then the start of the Russo-Ukrainian War in 2014, and