The Pacific-12 Conference is a collegiate athletic conference that operates in the Western United States. It participates in the NCAA's Division I; its football teams compete in the Football Bowl Subdivision, the higher of two levels of NCAA Division I football competition. The conference's 12 members, which are primarily flagship research universities in their respective regions, well-regarded academically, and with relatively large student enrollment, compete in 22 NCAA sports. It was created after the disbanding of the Pacific Coast Conference, whose principal members founded the Athletic Association of Western Universities in 1959, and went by the names Big Five, Big Six, Pacific-8, Pacific-10, becoming the Pacific-12 in 2011. Nicknamed the "Conference of Champions," the Pac-12 has won more NCAA National Team Championships than any other conference in history; the three schools with the most NCAA team championships belong to the Pac-12. With Arizona State's softball title in 2011, the conference won its 400th NCAA Championship. The current commissioner of the conference is Larry Scott who replaced Thomas C. Hansen, who retired in July 2009 after 26 years in that position. Prior to joining the Pac-10, Scott was Chairman and CEO of the Women's Tennis Association.