The league also introduced a new eight-year scheduling rotation designed so that all teams will play each other at least twice during those eight years, and play in every other team's stadium at least once. Under scheduling formulas in use from 1978 to 2001, two teams in different divisions have gone over 15 seasons without playing each other. Under the new scheduling formula, only two of a team's games each season are based on the previous season's record, down from four under the previous system. All teams play four interconference games. An analysis of win percentages in 2008 showed a statistical trend upwards for top teams since this change; the top team each year then averaged 14.2 wins, versus 13.4 previously.