Technological advances and increased revenues have led to significant changes in sports over time. Equipment evolved from basic materials to high-tech designs. Salaries rose dramatically from the 1920s to present day, with the average NFL salary reaching $2 million in 2009. Endorsement deals now provide additional income. Stadiums have grown larger with advanced amenities. Experts predict instant replay will expand to all sports, more pro teams in new locations, and potential payment of college athletes.