pre_text: table of contents in march 2008 , the fasb issued sfas no . 161 , disclosures about derivative instruments and hedging activities 2014an amendment of fasb statement no . 133 , which requires companies to provide additional disclosures about its objectives and strategies for using derivative instruments , how the derivative instruments and related hedged items are accounted for under sfas no . 133 , accounting for derivative instruments and hedging activities , and related interpretations , and how the derivative instruments and related hedged items affect the company 2019s financial statements . sfas no . 161 also requires companies to disclose information about credit risk-related contingent features in their hedged positions . sfas no . 161 is effective for fiscal years and interim periods beginning after november 15 , 2008 and is required to be adopted by the company beginning in the second quarter of fiscal 2009 . although the company will continue to evaluate the application of sfas no . 161 , management does not currently believe adoption will have a material impact on the company 2019s financial condition or operating results . liquidity and capital resources the following table presents selected financial information and statistics as of and for the three fiscal years ended september 27 , 2008 ( in millions ) : as of september 27 , 2008 , the company had $ 24.5 billion in cash , cash equivalents , and short-term investments , an increase of $ 9.1 billion from september 29 , 2007 . the principal components of this net increase were cash generated by operating activities of $ 9.6 billion , proceeds from the issuance of common stock under stock plans of $ 483 million and excess tax benefits from stock-based compensation of $ 757 million . these increases were partially offset by payments for acquisitions of property , plant , and equipment of $ 1.1 billion , payments made in connection with business acquisitions , net of cash acquired , of $ 220 million and payments for acquisitions of intangible assets of $ 108 million . the company 2019s cash generated by operating activities significantly exceeded its net income due primarily to the large increase in deferred revenue , net of deferred costs , associated with subscription accounting for iphone . the company 2019s short-term investment portfolio is invested primarily in highly rated securities with a minimum rating of single-a . as of september 27 , 2008 and september 29 , 2007 , $ 11.3 billion and $ 6.5 billion , respectively , of the company 2019s cash , cash equivalents , and short- term investments were held by foreign subsidiaries and are generally based in u.s . dollar-denominated holdings . the company had $ 117 million in net unrealized losses on its investment portfolio , primarily related to investments with stated maturities ranging from one to five years , as of september 27 , 2008 , and net unrealized losses of approximately $ 11 million on its investment portfolio , primarily related to investments with stated maturities from one to five years , as of september 29 , 2007 . the company has the intent and ability to hold such investments for a sufficient period of time to allow for recovery of the principal amounts invested . accordingly , none of these declines in fair value were recognized in the company 2019s statement of operations . the company believes its existing balances of cash , cash equivalents , and short-term investments will be sufficient to satisfy its working capital needs , capital expenditures , outstanding commitments , and other liquidity requirements associated with its existing operations over the next 12 months . capital assets the company 2019s cash payments for capital asset purchases were $ 1.1 billion during 2008 , consisting of $ 389 million for retail store facilities and $ 702 million for real estate acquisitions and corporate infrastructure including information systems enhancements . the company anticipates utilizing approximately $ 1.5 billion for capital asset purchases during 2009 , including approximately $ 400 million for retail facilities and approximately $ 1.1 billion for corporate facilities and infrastructure. .
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table: 2008 2007 2006
table: Cash, cash equivalents, and short-term investments $24,490 $15,386 $10,110
table: Accounts receivable, net $2,422 $1,637 $1,252
table: Inventory $509 $346 $270
table: Working capital $20,598 $12,676 $8,066
table: Annual operating cash flow $9,596 $5,470 $2,220
question: Analyse this data from a financial earnings document. between september 27 , 2008 and september 29 , 2007 how much in billions did the company 2019s cash , cash equivalents , and short- term investments held by foreign subsidiaries increase?