football leagues) later advance to the NFL, but no farming contracts exist among any teams, in part because the National Football League Players Association opposes the idea of an affiliated farm system on the grounds that its players would be at risk of unnecessary injury. During the mid-2000s, several NFL owners at least partially owned arena football teams, such as Jerry Jones (Dallas), Arthur Blank (Atlanta), Bud Adams (Tennessee), Tom Benson (New Orleans), and Pat Bowlen (Denver), but very rarely did they ever promote or demote any players between the AFL and NFL, due in part to significant differences in the playing schedules and the style of play between outdoor and indoor football. All of the NFL owners backed out of the league when it went bankrupt, was sold off and reorganized. In Canada, intercollegiate sport has never attained a similar level of following compared to the United States, mainly due to ice hockey being the most popular sport in the country. In hockey, the National Hockey League has historically overlooked intercollegiate sport in favour of other player development models. Nevertheless, the Canadian Football League has established itself as a niche league despite collecting only a fraction of the revenues commanded by the NFL. To recruit talented players, the league to a large extent relies on maintaining rules that are similar enough to American football so as to allow talented NCAA-trained players a reasonable prospect of adapting and being successful in the CFL, while retaining significant enough differences so as to ensure that the league is largely not in competition with the NFL for exactly the same type of players. In addition, to maintain the league's distinct Canadian identity, the league enforces a strict quota of Canadian players that must be on the rosters of all CFL teams. The Arena Football League had its own developmental league known as the af2 from 2000 to 2009. Basketball Traditionally, the NBA did not have a formal farm league, though unofficially, the Continental Basketball Association served as an NBA feeder league on and off through its existence. It mainly relies on the elite NCAA to produce NBA players, and thus the latter was often known as the "feeders". Since 2001, the NBA directly owns an entire farm league: the NBA G League (formerly the NBA D-League). The NBA G League started with eight teams in the fall of 2001. In March 2005, NBA