be one of the greatest heavyweight boxers of all time. In 2005, Louis was ranked as the best heavyweight of all time by the International Boxing Research Organization, and was ranked number one on The Ring magazine's list of the "100 greatest punchers of all time". Louis had the longest single reign as champion of any heavyweight boxer in history. Louis is widely regarded as the first person of African-American descent to achieve the status of a nationwide hero within the United States, and was also a focal point of anti-Nazi sentiment leading up to and during World War II. He was instrumental in integrating the game of golf, breaking the sport's color barrier in America by appearing under a sponsor's exemption in a PGA event in 1952. In the 1960s and 1970s, Muhammad Ali became an iconic figure, transformed the role and image of the African American athlete in America by his embrace of racial pride, and transcended the sport by refusing to serve in the Vietnam War. In the 1980s Mike Tyson emerged as a serious contender. Nicknamed "Iron Mike", Tyson won the heavyweight unification series to become world heavyweight champion at the age of 20 and the first undisputed champion in a decade. Tyson soon became the most widely known boxer since Ali due to an aura of unrestrained ferocity, such as that exuded by Jack Dempsey or Sonny Liston. His career culminated in Evander Holyfield vs. Mike Tyson II where he famously bit off a piece of Holyfield's ear. Since the late 1990s boxing has declined in popularity for a myriad of factors such as more sports entertainment options and combat alternatives such as MMA's UFC amongst a younger demographic. Lack of mainstream coverage in newspapers and access on major television networks. Also the lack of a US Heavyweight world champion. It was hoped in 2015 that the Floyd Mayweather Jr. vs. Manny Pacquiao fight would re-invigorate interest in the sport in the United States but because the fight was disappointing it was perceived as doing further harm to the image of the sport in the United States. Other Combat Sports Mixed martial arts in the United States largely developed in the 1990s, and has achieved popularity in the early 21st century. Many companies promote MMA cards, with the U.S. based Ultimate Fighting Championship (UFC) the most dominant. Traditional "folkstyle" wrestling is performed at the scholastic