Assumptions | Granted in 2017 for 2014 plan | Granted in 2016 for 2014 plan | Granted in 2015 for 2014 plan | ||||||
Stock price | 39.69 | 31.89 | 28.29 | ||||||
Expected option life | 6 | years | 6 | years | 6 | years | |||
Volatility | 19 | % | 20 | % | 20 | % | |||
Risk-free interest rate | 2.00 | % | 1.95 | % | 1.76 | % |