in millions , what was the average net change in discounted future cash flows for the three year period?
Important information:
table_11: ( in millions ) the net change for the year of 2009 is 1656 ; the net change for the year of 2008 is -8932 ( 8932 ) ; the net change for the year of 2007 is 4617 ;
table_13: ( in millions ) the end of year of 2009 is $ 5691 ; the end of year of 2008 is $ 4035 ; the end of year of 2007 is $ 12967 ;
table_14: ( in millions ) the net change for the year from discontinued operations of 2009 is $ - ; the net change for the year from discontinued operations of 2008 is $ 284 ; the net change for the year from discontinued operations of 2007 is $ 528 ;
Reasoning Steps:
Step: average1-1(net change for the year, none) = -886
Program:
table_average(net change for the year, none)
Program (Nested):
table_average(net change for the year, none)

Please answer the following financial question based on the context provided. Make sure to give the answer in raw number, not in percentage and without any units. If the question asks for percentage the value should be less than 1
Context:
supplementary information on oil and gas producing activities ( unaudited ) changes in the standardized measure of discounted future net cash flows .
Table
( in millions )                                                                           | 2009             | 2008             | 2007            
sales and transfers of oil and gas produced net of production andadministrative costs     | $ -4876 ( 4876 ) | $ -6863 ( 6863 ) | $ -4613 ( 4613 )
net changes in prices and production and administrative costs related tofuture production | 4840             | -18683 ( 18683 ) | 12344           
extensions discoveries and improved recovery less related costs                           | 1399             | 663              | 1816            
development costs incurred during the period                                              | 2786             | 1774             | 1569            
changes in estimated future development costs                                             | -3641 ( 3641 )   | -1436 ( 1436 )   | -1706 ( 1706 )  
revisions of previous quantity estimates                                                  | 5110             | 85               | 166             
net changes in purchases and sales of minerals in place                                   | -159 ( 159 )     | -13 ( 13 )       | 23              
accretion of discount                                                                     | 787              | 2724             | 1696            
net change in income taxes                                                                | -4441 ( 4441 )   | 12633            | -6647 ( 6647 )  
timing and other                                                                          | -149 ( 149 )     | 184              | -31 ( 31 )      
net change for the year                                                                   | 1656             | -8932 ( 8932 )   | 4617            
beginning of the year                                                                     | 4035             | 12967            | 8350            
end of year                                                                               | $ 5691           | $ 4035           | $ 12967         
net change for the year from discontinued operations                                      | $ -              | $ 284            | $ 528           
.
Question: 
in millions , what was the average net change in discounted future cash flows for the three year period?
Important information:
table_11: ( in millions ) the net change for the year of 2009 is 1656 ; the net change for the year of 2008 is -8932 ( 8932 ) ; the net change for the year of 2007 is 4617 ;
table_13: ( in millions ) the end of year of 2009 is $ 5691 ; the end of year of 2008 is $ 4035 ; the end of year of 2007 is $ 12967 ;
table_14: ( in millions ) the net change for the year from discontinued operations of 2009 is $ - ; the net change for the year from discontinued operations of 2008 is $ 284 ; the net change for the year from discontinued operations of 2007 is $ 528 ;
Reasoning Steps:
Step: average1-1(net change for the year, none) = -886
Program:
table_average(net change for the year, none)
Program (Nested):
table_average(net change for the year, none)
