table of contents primarily to certain undistributed foreign earnings for which no u.s . taxes are provided because such earnings are intended to be indefinitely reinvested outside the u.s . the lower effective tax rate in 2010 as compared to 2009 is due primarily to an increase in foreign earnings on which u.s . income taxes have not been provided as such earnings are intended to be indefinitely reinvested outside the u.s . as of september 25 , 2010 , the company had deferred tax assets arising from deductible temporary differences , tax losses , and tax credits of $ 2.4 billion , and deferred tax liabilities of $ 5.0 billion . management believes it is more likely than not that forecasted income , including income that may be generated as a result of certain tax planning strategies , together with future reversals of existing taxable temporary differences , will be sufficient to fully recover the deferred tax assets . the company will continue to evaluate the realizability of deferred tax assets quarterly by assessing the need for and amount of a valuation allowance . the internal revenue service ( the 201cirs 201d ) has completed its field audit of the company 2019s federal income tax returns for the years 2004 through 2006 and proposed certain adjustments . the company has contested certain of these adjustments through the irs appeals office . the irs is currently examining the years 2007 through 2009 . all irs audit issues for years prior to 2004 have been resolved . during the third quarter of 2010 , the company reached a tax settlement with the irs for the years 2002 through 2003 . in addition , the company is subject to audits by state , local , and foreign tax authorities . management believes that adequate provision has been made for any adjustments that may result from tax examinations . however , the outcome of tax audits cannot be predicted with certainty . if any issues addressed in the company 2019s tax audits are resolved in a manner not consistent with management 2019s expectations , the company could be required to adjust its provision for income taxes in the period such resolution occurs . liquidity and capital resources the following table presents selected financial information and statistics as of and for the three years ended september 25 , 2010 ( in millions ) : as of september 25 , 2010 , the company had $ 51 billion in cash , cash equivalents and marketable securities , an increase of $ 17 billion from september 26 , 2009 . the principal component of this net increase was the cash generated by operating activities of $ 18.6 billion , which was partially offset by payments for acquisition of property , plant and equipment of $ 2 billion and payments made in connection with business acquisitions , net of cash acquired , of $ 638 million . the company 2019s marketable securities investment portfolio is invested primarily in highly rated securities , generally with a minimum rating of single-a or equivalent . as of september 25 , 2010 and september 26 , 2009 , $ 30.8 billion and $ 17.4 billion , respectively , of the company 2019s cash , cash equivalents and marketable securities were held by foreign subsidiaries and are generally based in u.s . dollar-denominated holdings . the company believes its existing balances of cash , cash equivalents and marketable securities will be sufficient to satisfy its working capital needs , capital asset purchases , outstanding commitments and other liquidity requirements associated with its existing operations over the next 12 months. .
as of september 25 , 2010 , the company had $ 51 billion in cash , cash equivalents and marketable securities . what percentage of the change in 2010 was due to cash generated by operating activities?
.