was formerly used. The Gilchrist-Thomas process (or basic Bessemer process) was an improvement to the Bessemer process, made by lining the converter with a basic material to remove phosphorus. Another 19th-century steelmaking process was the Siemens-Martin process, which complemented the Bessemer process. It consisted of co-melting bar iron (or steel scrap) with pig iron. These methods of steel production were rendered obsolete by the Linz-Donawitz process of basic oxygen steelmaking (BOS), developed in 1952, and other oxygen steel making methods. Basic oxygen steelmaking is superior to previous steelmaking methods because the oxygen pumped into the furnace limited impurities, primarily nitrogen, that previously had entered from the air used, and because, with respect to the open hearth process, the same quantity of steel from a BOS process is manufactured in one-twelfth the time. Today, electric arc furnaces (EAF) are a common method of reprocessing scrap metal to create new steel. They can also be used for converting pig iron to steel, but they use a lot of electrical energy (about 440 kWh per metric ton), and are thus generally only economical when there is a plentiful supply of cheap electricity. Industry The steel industry is often considered an indicator of economic progress, because of the critical role played by steel in infrastructural and overall economic development. In 1980, there were more than 500,000 U.S. steelworkers. By 2000, the number of steelworkers had fallen to 224,000. The economic boom in China and India caused a massive increase in the demand for steel. Between 2000 and 2005, world steel demand increased by 6%. Since 2000, several Indian and Chinese steel firms have risen to prominence, such as Tata Steel (which bought Corus Group in 2007), Baosteel Group and Shagang Group. , though, ArcelorMittal is the world's largest steel producer. In 2005, the British Geological Survey stated China was the top steel producer with about one-third of the world share; Japan, Russia, and the US followed respectively. The large production capacity of steel results also in a significant amount of carbon dioxide emissions inherent related to the main production route. In 2021, it was estimated that around 7% of the global greenhouse gas emissions resulted from the steel industry. Reduction of these emissions are expected to come from a shift in the main production route using cokes, more recycling of steel and the application of carbon capture and storage or carbon capture and utilization