{"pre_text": ["material impact on the service cost and interest cost components of net periodic benefit costs for a 1% ( 1 % ) change in the assumed health care trend rate .", "for most of the participants in the u.s .", "plan , aon 2019s liability for future plan cost increases for pre-65 and medical supplement plan coverage is limited to 5% ( 5 % ) per annum .", "because of this cap , net employer trend rates for these plans are effectively limited to 5% ( 5 % ) per year in the future .", "during 2007 , aon recognized a plan amendment which phases out post-65 retiree coverage in its u.s .", "plan over the next three years .", "the impact of this amendment on net periodic benefit cost is being recognized over the average remaining service life of the employees .", "14 .", "stock compensation plans the following table summarizes stock-based compensation expense recognized in continuing operations in the consolidated statements of income in compensation and benefits ( in millions ) : ."], "post_text": ["during 2009 , the company converted its stock administration system to a new service provider .", "in connection with this conversion , a reconciliation of the methodologies and estimates utilized was performed , which resulted in a $ 12 million reduction of expense for the year ended december 31 , 2009 .", "stock awards stock awards , in the form of rsus , are granted to certain employees and consist of both performance-based and service-based rsus .", "service-based awards generally vest between three and ten years from the date of grant .", "the fair value of service-based awards is based upon the market value of the underlying common stock at the date of grant .", "with certain limited exceptions , any break in continuous employment will cause the forfeiture of all unvested awards .", "compensation expense associated with stock awards is recognized over the service period .", "dividend equivalents are paid on certain service-based rsus , based on the initial grant amount .", "performance-based rsus have been granted to certain employees .", "vesting of these awards is contingent upon meeting various individual , divisional or company-wide performance conditions , including revenue generation or growth in revenue , pretax income or earnings per share over a one- to five-year period .", "the performance conditions are not considered in the determination of the grant date fair value for these awards .", "the fair value of performance-based awards is based upon the market price of the underlying common stock at the date of grant .", "compensation expense is recognized over the performance period , and in certain cases an additional vesting period , based on management 2019s estimate of the number of units expected to vest .", "compensation expense is adjusted to reflect the actual number of shares paid out at the end of the programs .", "the actual payout of shares under these performance- based plans may range from 0-200% ( 0-200 % ) of the number of units granted , based on the plan .", "dividend equivalents are generally not paid on the performance-based rsus .", "during 2010 , the company granted approximately 1.6 million shares in connection with the completion of the 2007 leadership performance plan ( 2018 2018lpp 2019 2019 ) cycle and 84000 shares related to other performance plans .", "during 2010 , 2009 and 2008 , the company granted approximately 3.5 million ."], "table": [["years ended december 31", "2010", "2009", "2008"], ["rsus", "$ 138", "$ 124", "$ 132"], ["performance plans", "62", "60", "67"], ["stock options", "17", "21", "24"], ["employee stock purchase plans", "4", "4", "3"], ["total stock-based compensation expense", "221", "209", "226"], ["tax benefit", "75", "68", "82"], ["stock-based compensation expense net of tax", "$ 146", "$ 141", "$ 144"]], "table_ori": [["Years ended December 31", "2010", "2009", "2008"], ["RSUs", "$138", "$124", "$132"], ["Performance plans", "62", "60", "67"], ["Stock options", "17", "21", "24"], ["Employee stock purchase plans", "4", "4", "3"], ["Total stock-based compensation expense", "221", "209", "226"], ["Tax benefit", "75", "68", "82"], ["Stock-based compensation expense, net of tax", "$146", "$141", "$144"]]}

Question: what was the average total stock-based compensation expense from 2008 to 2010 in millions
Evidence:
table_5: years ended december 31 the total stock-based compensation expense of 2010 is 221 ; the total stock-based compensation expense of 2009 is 209 ; the total stock-based compensation expense of 2008 is 226 ;
Program: add(221, 209), add(#0, 226), add(#1, const_3), divide(#2, const_2)
Answer:
str_answer: 218
exe_answer: 329.5