Fox Broadcasting Company (often shortened to Fox and stylized as FOX) is an American commercial broadcast television network owned by Fox Entertainment Group, a subsidiary of 21st Century Fox. The network is headquartered at 20th Century Fox studio on Pico Boulevard in Century City of Los Angeles with additional major offices and production facilities at the Fox Television Center in nearby West Los Angeles and Fox Broadcasting Center in the Yorkville neighborhood of Manhattan, New York City. It is the third largest major television network in the world based on total revenues, assets and international coverage. 

Launched on October 9, 1986 as a competitor to the Big Three television networks (ABC, NBC and CBS), Fox went on to become the most successful attempt at a fourth television network. It was the highest-rated broadcast network in the 18–49 demographic from 2004 to 2012, and earned the position as the most-watched American television network in total viewership during the 2007–08 season. Fox and its affiliated companies operate many entertainment channels in international markets, although these do not necessarily air the same programming as the U.S. network. Most viewers in Canada have access to at least one U.S.-based Fox affiliate, either over-the-air or through a pay television provider, although Fox's National Football League telecasts and most of its prime time programming are subject to simultaneous substitution regulations for cable and satellite providers imposed by the Canadian Radio-television and Telecommunications Commission (CRTC) to protect rights held by domestically based networks.
How many exactly?
unknown