Please answer the given financial question based on the context.
Context: supplementary information on oil and gas producing activities ( unaudited ) c o n t i n u e d summary of changes in standardized measure of discounted future net cash flows relating to proved oil and gas reserves ( in millions ) 2008 2007 2006 sales and transfers of oil and gas produced , net of production , transportation and administrative costs $ ( 7141 ) $ ( 4887 ) $ ( 5312 ) net changes in prices and production , transportation and administrative costs related to future production ( 18290 ) 12845 ( 1342 ) .
|( in millions )|2008|2007|2006|
|sales and transfers of oil and gas produced net of production transportation and administrative costs|$ -7141 ( 7141 )|$ -4887 ( 4887 )|$ -5312 ( 5312 )|
|net changes in prices and production transportation and administrative costs related to future production|-18290 ( 18290 )|12845|-1342 ( 1342 )|
|extensions discoveries and improved recovery less related costs|663|1816|1290|
|development costs incurred during the period|1916|1654|1251|
|changes in estimated future development costs|-1584 ( 1584 )|-1727 ( 1727 )|-527 ( 527 )|
|revisions of previous quantity estimates|53|290|1319|
|net changes in purchases and sales of minerals in place|-13 ( 13 )|23|30|
|accretion of discount|2796|1726|1882|
|net change in income taxes|12805|-6751 ( 6751 )|-660 ( 660 )|
|timing and other|-96 ( 96 )|-12 ( 12 )|-14 ( 14 )|
|net change for the year|-8891 ( 8891 )|4977|-2083 ( 2083 )|
|beginning of the year|13495|8518|10601|
|end of year|$ 4604|$ 13495|$ 8518|
|net change for the year from discontinued operations|$ 2013|$ 2013|$ -216 ( 216 )|
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Question: what is the average discounted cash flow balance for the three year period , in millions?
Answer:
8872.33333