{"pre_text": ["american tower corporation and subsidiaries notes to consolidated financial statements assessments in each of the tax jurisdictions resulting from these examinations .", "the company believes that adequate provisions have been made for income taxes for all periods through december 31 , 2010 .", "12 .", "stock-based compensation the company recognized stock-based compensation of $ 52.6 million , $ 60.7 million and $ 54.8 million for the years ended december 31 , 2010 , 2009 and 2008 , respectively .", "stock-based compensation for the year ended december 31 , 2009 included $ 6.9 million related to the modification of the vesting and exercise terms for certain employee 2019s equity awards .", "the company did not capitalize any stock-based compensation during the years ended december 31 , 2010 and 2009 .", "summary of stock-based compensation plans 2014the company maintains equity incentive plans that provide for the grant of stock-based awards to its directors , officers and employees .", "under the 2007 equity incentive plan ( 201c2007 plan 201d ) , which provides for the grant of non-qualified and incentive stock options , as well as restricted stock units , restricted stock and other stock-based awards , exercise prices in the case of non-qualified and incentive stock options are not less than the fair market value of the underlying common stock on the date of grant .", "equity awards typically vest ratably over various periods , generally four years , and generally expire ten years from the date of grant .", "stock options 2014as of december 31 , 2010 , the company had the ability to grant stock-based awards with respect to an aggregate of 22.0 million shares of common stock under the 2007 plan .", "the fair value of each option grant is estimated on the date of grant using the black-scholes option pricing model based on the assumptions noted in the table below .", "the risk-free treasury rate is based on the u.s .", "treasury yield in effect at the accounting measurement date .", "the expected life ( estimated period of time outstanding ) was estimated using the vesting term and historical exercise behavior of company employees .", "the expected volatility was based on historical volatility for a period equal to the expected life of the stock options .", "key assumptions used to apply this pricing model are as follows: ."], "post_text": ["the weighted average grant date fair value per share during the years ended december 31 , 2010 , 2009 and 2008 was $ 15.03 , $ 8.90 and $ 9.55 , respectively .", "the intrinsic value of stock options exercised during the years ended december 31 , 2010 , 2009 and 2008 was $ 62.7 million , $ 40.1 million and $ 99.1 million , respectively .", "as of december 31 , 2010 , total unrecognized compensation expense related to unvested stock options was approximately $ 27.7 million and is expected to be recognized over a weighted average period of approximately two years .", "the amount of cash received from the exercise of stock options was approximately $ 129.1 million during the year ended december 31 , 2010 .", "during the year ended december 31 , 2010 , the company realized approximately $ 0.3 million of state tax benefits from the exercise of stock options. ."], "table": [["", "2010", "2009", "2008"], ["range of risk-free interest rate", "1.41% ( 1.41 % ) 2013 2.39% ( 2.39 % )", "1.41% ( 1.41 % ) 2013 2.04% ( 2.04 % )", "1.44% ( 1.44 % ) 2013 3.05% ( 3.05 % )"], ["weighted average risk-free interest rate", "2.35% ( 2.35 % )", "1.71% ( 1.71 % )", "1.89% ( 1.89 % )"], ["expected life of option grants", "4.60 years", "4.00 years", "4.00 years"], ["range of expected volatility of underlying stock price", "37.11% ( 37.11 % ) 2013 37.48% ( 37.48 % )", "36.00% ( 36.00 % ) 2013 36.63% ( 36.63 % )", "28.51% ( 28.51 % ) 2013 35.30% ( 35.30 % )"], ["weighted average expected volatility of underlying stock price", "37.14% ( 37.14 % )", "36.23% ( 36.23 % )", "29.10% ( 29.10 % )"], ["expected annual dividends", "n/a", "n/a", "n/a"]], "table_ori": [["", "2010", "2009", "2008"], ["Range of risk-free interest rate", "1.41% – 2.39%", "1.41% – 2.04%", "1.44% – 3.05%"], ["Weighted average risk-free interest rate", "2.35%", "1.71%", "1.89%"], ["Expected life of option grants", "4.60 years", "4.00 years", "4.00 years"], ["Range of expected volatility of underlying stock price", "37.11% – 37.48%", "36.00% – 36.63%", "28.51% – 35.30%"], ["Weighted average expected volatility of underlying stock price", "37.14%", "36.23%", "29.10%"], ["Expected annual dividends", "N/A", "N/A", "N/A"]]}

Question: what was the percent of the change in the weighted average risk-free interest rate
Evidence:
table_2: the weighted average risk-free interest rate of 2010 is 2.35% ( 2.35 % ) ; the weighted average risk-free interest rate of 2009 is 1.71% ( 1.71 % ) ; the weighted average risk-free interest rate of 2008 is 1.89% ( 1.89 % ) ;
Program: subtract(2.35, 1.71), divide(#0, 1.71)
Answer:
str_answer: 37.4%
exe_answer: 0.37427