tons), manganese ore (3 billion tons), chalk and limestone (1.5 billion tons) are also large in Ukraine. The domestic industrial sector suffers from constant energy shortages and energy supply payment debts totaling about $792 million at the end of 1995. In 2019, Ukraine was the 7th largest world producer of iron ore, the world's 8th largest producer of manganese, 6th largest producer of titanium, and 7th largest producer worldwide of graphite. Ukraine was the world's 9th largest producer of uranium in 2018. Ukraine supplies about 50% of the world's neon gas and 40% of its krypton, both of which are needed for the production of semiconductors. It is estimated that over 90% of U.S. semiconductor-grade neon supplies are imported from Ukraine. Iron and steel Ukraine is rich in mineral deposits, including iron ore (of which it once produced 50 percent of the entire Soviet output), manganese ore (of which it produced 40 percent of world output during the Soviet era), mercury, titanium, and nickel. Ukraine has a major ferrous metal industry, producing cast iron, steel and pipes. Among its economy leading companies in that field are Metinvest, Kryvorizhstal, AzovStal, Ilyich Steel & Iron Works, and others. As of 2012, Ukraine is the world's tenth largest steel producer (according to the World Steel Association). Chemical industry Another important branch is the country's chemical industry which includes the production of coke, mineral fertilizers and sulfuric acid. Defense industry Ukraine's defense industry is organized around Ukroboronprom, a state owned conglomerate of over 130 companies. These companies include Soviet era giants such as Ivchenko-Progress aircraft design bureau that was opened in 1945, to newer companies such as RPC Fort which came into existence in the 1990s. Ukraine is among the top 10 arms exporters in the world. The signing of recent large contracts may put Ukraine into 6th place among biggest arms traders, after the United States, Russian Federation, France, Germany and Israel. The output of Ukrainian defense plants grew 58% in 2009, with largest growth reported by aircraft builders (77%) and ship builders (71%). In 2013, Ukraine's defense sector manufactured a total of 11.7 billion UAH worth of goods, 10 billion UAH of which were exported. In the first 9 months of 2014 Ukraine's defense sector produced a record 13 billion UAH worth of goods. The increase was largely due to government orders for the War in Donbas. Fuel and energy complex Due