A billionaire, in countries that use the short scale number naming system, is a person with a net worth of at least one billion (1,000,000,000; a thousand million) units of a given currency, usually major currencies such as the United States dollar, the euro, or the pound sterling. The American business magazine Forbes produces a complete global list of known U.S. dollar billionaires every year, and updates an Internet version of this list in real time. The American oil magnate John D. Rockefeller became the world's first confirmed U.S. dollar billionaire in 1916; as of 2015, there are over 1,800 U.S. dollar billionaires worldwide, with a combined wealth of over US$7 trillion.