table of contents adobe inc .notes to consolidated financial statements ( continued ) stock options the 2003 plan allows us to grant options to all employees , including executive officers , outside consultants and non- employee directors .this plan will continue until the earlier of ( i ) termination by the board or ( ii ) the date on which all of the shares available for issuance under the plan have been issued and restrictions on issued shares have lapsed .option vesting periods used in the past were generally four years and expire seven years from the effective date of grant .we eliminated the use of stock option grants for all employees and non-employee directors but may choose to issue stock options in the future .performance share programs our 2018 , 2017 and 2016 performance share programs aim to help focus key employees on building stockholder value , provide significant award potential for achieving outstanding company performance and enhance the ability of the company to attract and retain highly talented and competent individuals .the executive compensation committee of our board of directors approves the terms of each of our performance share programs , including the award calculation methodology , under the terms of our 2003 plan .shares may be earned based on the achievement of an objective relative total stockholder return measured over a three-year performance period .performance share awards will be awarded and fully vest upon the later of the executive compensation committee's certification of the level of achievement or the three-year anniversary of each grant .program participants generally have the ability to receive up to 200% ( 200 % ) of the target number of shares originally granted .on january 24 , 2018 , the executive compensation committee approved the 2018 performance share program , the terms of which are similar to prior year performance share programs as discussed above .as of november 30 , 2018 , the shares awarded under our 2018 , 2017 and 2016 performance share programs are yet to be achieved .issuance of shares upon exercise of stock options , vesting of restricted stock units and performance shares , and purchases of shares under the espp , we will issue treasury stock .if treasury stock is not available , common stock will be issued .in order to minimize the impact of on-going dilution from exercises of stock options and vesting of restricted stock units and performance shares , we instituted a stock repurchase program .see note 12 for information regarding our stock repurchase programs .valuation of stock-based compensation stock-based compensation cost is measured at the grant date based on the fair value of the award .our performance share awards are valued using a monte carlo simulation model .the fair value of the awards are fixed at grant date and amortized over the longer of the remaining performance or service period .we use the black-scholes option pricing model to determine the fair value of espp shares .the determination of the fair value of stock-based payment awards on the date of grant using an option pricing model is affected by our stock price as well as assumptions regarding a number of complex and subjective variables .these variables include our expected stock price volatility over the expected term of the awards , actual and projected employee stock option exercise behaviors , a risk-free interest rate and any expected dividends .the expected term of espp shares is the average of the remaining purchase periods under each offering period .the assumptions used to value employee stock purchase rights were as follows: .
[['', '2018', '2017', '2016'], ['expected life ( in years )', '0.5 - 2.0', '0.5 - 2.0', '0.5 - 2.0'], ['volatility', '26% ( 26 % ) - 29% ( 29 % )', '22% ( 22 % ) - 27% ( 27 % )', '26 - 29% ( 29 % )'], ['risk free interest rate', '1.54% ( 1.54 % ) - 2.52% ( 2.52 % )', '0.62% ( 0.62 % ) - 1.41% ( 1.41 % )', '0.37 - 1.06% ( 1.06 % )']]
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Question: what is the average volatility used to value employee stock purchase rights in 2018?
Answer: 27.5%