frequency ( aehf ) system , orion , global positioning satellite ( gps ) iii system , geostationary operational environmental satellite r-series ( goes-r ) , and mobile user objective system ( muos ) . operating profit for our space systems business segment includes our share of earnings for our investment in united launch alliance ( ula ) , which provides expendable launch services to the u.s . government . space systems 2019 operating results included the following ( in millions ) : .

Table: 2013 2012 2011 net sales $ 7958 $ 8347 $ 8161 operating profit 1045 1083 1063 operating margins 13.1% ( 13.1 % ) 13.0% ( 13.0 % ) 13.0% ( 13.0 % ) backlog at year-end 20500 18100 16000

2013 compared to 2012 space systems 2019 net sales for 2013 decreased $ 389 million , or 5% ( 5 % ) , compared to 2012 . the decrease was primarily attributable to lower net sales of approximately $ 305 million for commercial satellite programs due to fewer deliveries ( zero delivered during 2013 compared to two for 2012 ) ; and about $ 290 million for the orion program due to lower volume . the decreases were partially offset by higher net sales of approximately $ 130 million for government satellite programs due to net increased volume ; and about $ 65 million for strategic and defensive missile programs ( primarily fbm ) due to increased volume and risk retirements . the increase for government satellite programs was primarily attributable to higher volume on aehf and other programs , partially offset by lower volume on goes-r , muos , and sbirs programs . space systems 2019 operating profit for 2013 decreased $ 38 million , or 4% ( 4 % ) , compared to 2012 . the decrease was primarily attributable to lower operating profit of approximately $ 50 million for the orion program due to lower volume and risk retirements and about $ 30 million for government satellite programs due to decreased risk retirements , which were partially offset by higher equity earnings from joint ventures of approximately $ 35 million . the decrease in operating profit for government satellite programs was primarily attributable to lower risk retirements for muos , gps iii , and other programs , partially offset by higher risk retirements for the sbirs and aehf programs . operating profit for 2013 included about $ 15 million of charges , net of recoveries , related to the november 2013 restructuring plan . adjustments not related to volume , including net profit booking rate adjustments and other matters , were approximately $ 15 million lower for 2013 compared to 2012 . 2012 compared to 2011 space systems 2019 net sales for 2012 increased $ 186 million , or 2% ( 2 % ) , compared to 2011 . the increase was attributable to higher net sales of approximately $ 150 million due to increased commercial satellite deliveries ( two commercial satellites delivered in 2012 compared to one during 2011 ) ; about $ 125 million from the orion program due to higher volume and an increase in risk retirements ; and approximately $ 70 million from increased volume on various strategic and defensive missile programs . partially offsetting the increases were lower net sales of approximately $ 105 million from certain government satellite programs ( primarily sbirs and muos ) as a result of decreased volume and a decline in risk retirements ; and about $ 55 million from the nasa external tank program , which ended in connection with the completion of the space shuttle program in 2011 . space systems 2019 operating profit for 2012 increased $ 20 million , or 2% ( 2 % ) , compared to 2011 . the increase was attributable to higher operating profit of approximately $ 60 million from commercial satellite programs due to increased deliveries and reserves recorded in 2011 ; and about $ 40 million from the orion program due to higher risk retirements and increased volume . partially offsetting the increases was lower operating profit of approximately $ 45 million from lower volume and risk retirements on certain government satellite programs ( primarily sbirs ) ; about $ 20 million from lower risk retirements and lower volume on the nasa external tank program , which ended in connection with the completion of the space shuttle program in 2011 ; and approximately $ 20 million from lower equity earnings as a decline in launch related activities at ula partially was offset by the resolution of contract cost matters associated with the wind-down of united space alliance ( usa ) . adjustments not related to volume , including net profit booking rate adjustments described above , were approximately $ 15 million higher for 2012 compared to 2011 . equity earnings total equity earnings recognized by space systems ( primarily ula in 2013 ) represented approximately $ 300 million , or 29% ( 29 % ) of this segment 2019s operating profit during 2013 . during 2012 and 2011 , total equity earnings recognized by space systems from ula , usa , and the u.k . atomic weapons establishment joint venture represented approximately $ 265 million and $ 285 million , or 24% ( 24 % ) and 27% ( 27 % ) of this segment 2019s operating profit. .

Question: what was the average net sales from 2011 to 2013
Answer: 8155.3
Calculation: divide(add(add(add(7958, 8347), 8161), const_3), const_2)