The following table presents the weighted-average assumptions used in the option pricing model for the 2013, 2012 and 2011 stock option grants. The expected life of the options represents the period of time the options are expected to be outstanding and is based on historical trends. Expected stock price volatility is generally based on the historical volatility of the Company’s stock for a period approximating the expected life. The expected dividend yield is based on the Company’s most recent annual dividend rate. The risk-free interest rate is based on the U.S. Treasury yield curve in effect at the time of grant with a term equal to the expected life.
Weighted-average assumptions
|
| | | | | | | | | |
| 2013 |
| 2012 |
| 2011 |
|
Expected dividend yield | 3.5 | % | 2.8 | % | 3.2 | % |
Expected stock price volatility | 20.6 | % | 20.8 | % | 21.5 | % |
Risk-free interest rate | 1.2 | % | 1.1 | % | 2.8 | % |
Expected life of options (in years) | 6.1 |
| 6.1 |
| 6.3 |
|
Fair value per option granted | $ | 11.09 |
| $ | 13.65 |
| $ | 12.18 |
|
