From ESPN Big Ten blogger, Adam Rittenberg.
Michigan: 20 returning starters (9 offense*, 9 defense, 2 special teams)Purdue: 18 returning starters (7 offense*, 9 defense, 2 special teams)
Northwestern: 17 returning starters (9 offense*, 7 defense, 1 special teams)
Penn State: 16 returning starters (7 offense*, 8 defense, 1 special teams)
Indiana: 15 returning starters (6 offense, 7 defense, 2 special teams)
Minnesota: 15 returning starters (5 offense, 9 defense, 1 special teams)
Illinois: 13 returning starters (6 offense*, 6 defense, 1 special teams)
Michigan State: 13 returning starters (6 offense*, 6 defense, 1 special teams)
Ohio State: 13 returning starters (8 offense*, 4 defense, 1 special teams)
Nebraska: 12 returning starters (5 offense*, 7 defense, 0 special teams)
Wisconsin: 12 returning starters (4 offense, 6 defense, 2 special teams)
Iowa: 10 returning starters (5 offense, 4 defense, 1 special teams)
*-includes starting quarterback
LINK