{"pre_text": ["weighted average fair values and valuation assumptions used to value performance unit and performance stock grants during the years ended december 31 , 2016 , 2015 and 2014 were as follows: ."], "post_text": ["expected volatility is based on the term-matched historical volatility over the simulated term , which is calculated as the time between the grant date and the end of the performance period .", "the risk-free interest rate is based on a 3.25 year zero-coupon risk-free interest rate derived from the treasury constant maturities yield curve on the grant date .", "at december 31 , 2016 , unrecognized compensation expense related to performance units totaled $ 10 million .", "such unrecognized expense will be amortized on a straight-line basis over a weighted average period of 3.0 years .", "pension plans .", "eog has a defined contribution pension plan in place for most of its employees in the united states .", "eog's contributions to the pension plan are based on various percentages of compensation and , in some instances , are based upon the amount of the employees' contributions .", "eog's total costs recognized for the plan were $ 34 million , $ 36 million and $ 41 million for 2016 , 2015 and 2014 , respectively .", "in addition , eog's trinidadian subsidiary maintains a contributory defined benefit pension plan and a matched savings plan .", "eog's united kingdom subsidiary maintains a pension plan which includes a non-contributory defined contribution pension plan and a matched defined contribution savings plan .", "these pension plans are available to most employees of the trinidadian and united kingdom subsidiaries .", "eog's combined contributions to these plans were $ 1 million , $ 1 million and $ 5 million for 2016 , 2015 and 2014 , respectively .", "for the trinidadian defined benefit pension plan , the benefit obligation , fair value of plan assets and accrued benefit cost totaled $ 8 million , $ 7 million and $ 0.3 million , respectively , at december 31 , 2016 , and $ 9 million , $ 7 million and $ 0.2 million , respectively , at december 31 , 2015 .", "in connection with the divestiture of substantially all of its canadian assets in the fourth quarter of 2014 , eog has elected to terminate the canadian non-contributory defined benefit pension plan .", "postretirement health care .", "eog has postretirement medical and dental benefits in place for eligible united states and trinidad employees and their eligible dependents , the costs of which are not material .", "8 .", "commitments and contingencies letters of credit and guarantees .", "at december 31 , 2016 and 2015 , respectively , eog had standby letters of credit and guarantees outstanding totaling approximately $ 226 million and $ 272 million , primarily representing guarantees of payment or performance obligations on behalf of subsidiaries .", "as of february 20 , 2017 , there were no demands for payment under these guarantees. ."], "table": [["", "2016", "2015", "2014"], ["weighted average fair value of grants", "$ 119.10", "$ 80.64", "$ 119.27"], ["expected volatility", "32.48% ( 32.48 % )", "29.35% ( 29.35 % )", "32.18% ( 32.18 % )"], ["risk-free interest rate", "1.15% ( 1.15 % )", "1.07% ( 1.07 % )", "1.18% ( 1.18 % )"]], "table_ori": [["", "2016", "2015", "2014"], ["Weighted Average Fair Value of Grants", "$119.10", "$80.64", "$119.27"], ["Expected Volatility", "32.48%", "29.35%", "32.18%"], ["Risk-Free Interest Rate", "1.15%", "1.07%", "1.18%"]]}

Question: considering the years 2014-2016 , what is the average expected volatility?
Evidence:
table_2: the expected volatility of 2016 is 32.48% ( 32.48 % ) ; the expected volatility of 2015 is 29.35% ( 29.35 % ) ; the expected volatility of 2014 is 32.18% ( 32.18 % ) ;
Program: table_average(expected volatility, none)
Answer:
str_answer: 31.34%
exe_answer: 0.31337