2013 | 2012 | 2011 | ||||||||||||||||||||||||||||
Options | Shares in millions | Weighted- average exercise price | Weighted- average remaining contractual life in years | Aggregate intrinsic value in millions | Shares in millions | Weighted- average exercise price | Shares in millions | Weighted- average exercise price | ||||||||||||||||||||||
Outstanding at beginning of year | 27.4 | $ | 59.86 | 31.7 | $ | 47.77 | 37.4 | $ | 42.47 | |||||||||||||||||||||
Granted | 3.7 | 94.36 | 4.9 | 99.63 | 3.9 | 75.97 | ||||||||||||||||||||||||
Exercised | (5.7 | ) | 40.12 | (8.6 | ) | 38.51 | (9.0 | ) | 37.46 | |||||||||||||||||||||
Forfeited/expired | (0.3 | ) | 79.15 | (0.6 | ) | 55.28 | (0.6 | ) | 55.00 | |||||||||||||||||||||
Outstanding at end of year | 25.1 | $ | 69.15 | 5.9 | $ | 713.7 | 27.4 | $ | 59.86 | 31.7 | $ | 47.77 | ||||||||||||||||||
Exercisable at end of year | 15.6 | $ | 56.43 | 4.5 | $ | 638.6 | 17.1 | 21.9 | ||||||||||||||||||||||