[["", "2015", "2014", "2013"], ["grant-date fair value", "$ 81.99 2013 $ 85.05", "$ 70.18 2013 $ 81.05", "$ 61.27 2013 $ 63.48"], ["risk-free interest rate", "1.06% ( 1.06 % )", "0.54% ( 0.54 % )", "0.26% ( 0.26 % ) 2013 0.36% ( 0.36 % )"], ["volatility factor", "26.2% ( 26.2 % )", "28.8% ( 28.8 % )", "30.3% ( 30.3 % )"], ["contractual term ( years )", "2.89", "2.89", "3.0"]]