In recent years almost all professional basketball players in the United States have come from the college ranks; professional teams conduct annual drafts to select promising players. The principal professional league in the United States is governed by the National Basketball Association (NBA), formed in 1949. With the addition of 2 new teams in 1994, the NBA grew to 29 teams, in 2 conferences (Eastern and Western) made up of 4 regional divisions. Play-offs are held at the end of each 82-game season to determine the league champion. The NBA also gives a number of annual awards, including awards for most valuable player and rookie of the year.