what were total development costs in millions for the three year period?
Important information:
table_4: ( in millions ) the development costs incurred during the period of 2011 is 1899 ; the development costs incurred during the period of 2010 is 2546 ; the development costs incurred during the period of 2009 is 2786 ;
table_5: ( in millions ) the changes in estimated future development costs of 2011 is -1349 ( 1349 ) ; the changes in estimated future development costs of 2010 is -2153 ( 2153 ) ; the changes in estimated future development costs of 2009 is -3773 ( 3773 ) ;
table_13: ( in millions ) the end of year of 2011 is $ 13928 ; the end of year of 2010 is $ 9280 ; the end of year of 2009 is $ 5655 ;
Reasoning Steps:
Step: sum2-1(development costs incurred during the period, none) = 7231
Program:
table_sum(development costs incurred during the period, none)
Program (Nested):
table_sum(development costs incurred during the period, 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 ( in millions ) 2011 2010 2009 .
Table
( in millions )                                                                            | 2011             | 2010             | 2009            
sales and transfers of oil and gas produced net of production and administrative costs     | $ -7922 ( 7922 ) | $ -6330 ( 6330 ) | $ -4876 ( 4876 )
net changes in prices and production and administrative costs related to future production | 12313            | 9843             | 4840            
extensions discoveries and improved recovery less related costs                            | 1454             | 1268             | 1399            
development costs incurred during the period                                               | 1899             | 2546             | 2786            
changes in estimated future development costs                                              | -1349 ( 1349 )   | -2153 ( 2153 )   | -3773 ( 3773 )  
revisions of previous quantity estimates                                                   | 2526             | 1117             | 5110            
net changes in purchases and sales of minerals in place                                    | 233              | -20 ( 20 )       | -159 ( 159 )    
accretion of discount                                                                      | 2040             | 1335             | 787             
net change in income taxes                                                                 | -6676 ( 6676 )   | -4231 ( 4231 )   | -4345 ( 4345 )  
timing and other                                                                           | 130              | 250              | -149 ( 149 )    
net change for the year                                                                    | 4648             | 3625             | 1620            
beginning of the year                                                                      | 9280             | 5655             | 4035            
end of year                                                                                | $ 13928          | $ 9280           | $ 5655          
.
Question: 
what were total development costs in millions for the three year period?
Important information:
table_4: ( in millions ) the development costs incurred during the period of 2011 is 1899 ; the development costs incurred during the period of 2010 is 2546 ; the development costs incurred during the period of 2009 is 2786 ;
table_5: ( in millions ) the changes in estimated future development costs of 2011 is -1349 ( 1349 ) ; the changes in estimated future development costs of 2010 is -2153 ( 2153 ) ; the changes in estimated future development costs of 2009 is -3773 ( 3773 ) ;
table_13: ( in millions ) the end of year of 2011 is $ 13928 ; the end of year of 2010 is $ 9280 ; the end of year of 2009 is $ 5655 ;
Reasoning Steps:
Step: sum2-1(development costs incurred during the period, none) = 7231
Program:
table_sum(development costs incurred during the period, none)
Program (Nested):
table_sum(development costs incurred during the period, none)
