$ 15 million for fire control programs due to increased deliveries ( primarily apache ) , partially offset by lower risk retirements ( primarily sniper ae ) . adjustments not related to volume , including net profit booking rate adjustments and other matters , were approximately $ 95 million lower for 2014 compared to 2013 . backlog backlog increased in 2015 compared to 2014 primarily due to higher orders on pac-3 , lantirn/sniper and certain tactical missile programs , partially offset by lower orders on thaad . backlog decreased in 2014 compared to 2013 primarily due to lower orders on thaad and fire control systems programs , partially offset by higher orders on certain tactical missile programs and pac-3 . trends we expect mfc 2019s net sales to be flat or experience a slight decline in 2016 as compared to 2015 . operating profit is expected to decrease by approximately 20 percent , driven by contract mix and fewer risk retirements in 2016 compared to 2015 . accordingly , operating profit margin is expected to decline from 2015 levels . mission systems and training as previously described , on november 6 , 2015 , we acquired sikorsky and aligned the sikorsky business under our mst business segment . the results of the acquired sikorsky business have been included in our financial results from the november 6 , 2015 acquisition date through december 31 , 2015 . as a result , our consolidated operating results and mst business segment operating results for the year ended december 31 , 2015 do not reflect a full year of sikorsky operations . our mst business segment provides design , manufacture , service and support for a variety of military and civil helicopters , ship and submarine mission and combat systems ; mission systems and sensors for rotary and fixed-wing aircraft ; sea and land-based missile defense systems ; radar systems ; the littoral combat ship ( lcs ) ; simulation and training services ; and unmanned systems and technologies . in addition , mst supports the needs of customers in cybersecurity and delivers communication and command and control capabilities through complex mission solutions for defense applications . mst 2019s major programs include black hawk and seahawk helicopters , aegis combat system ( aegis ) , lcs , space fence , advanced hawkeye radar system , and tpq-53 radar system . mst 2019s operating results included the following ( in millions ) : .
what was the average operating profit for mst from 2013 to 2015
2015 compared to 2014 mst 2019s net sales in 2015 increased $ 359 million , or 4% ( 4 % ) , compared to 2014 . the increase was attributable to net sales of approximately $ 400 million from sikorsky , net of adjustments required to account for the acquisition of this business in the fourth quarter of 2015 ; and approximately $ 220 million for integrated warfare systems and sensors programs , primarily due to the ramp-up of recently awarded programs ( space fence ) . these increases were partially offset by lower net sales of approximately $ 150 million for undersea systems programs due to decreased volume as a result of in-theater force reductions ( primarily persistent threat detection system ) ; and approximately $ 105 million for ship and aviation systems programs primarily due to decreased volume ( merlin capability sustainment program ) . mst 2019s operating profit in 2015 decreased $ 92 million , or 10% ( 10 % ) , compared to 2014 . operating profit decreased by approximately $ 75 million due to performance matters on an international program ; approximately $ 45 million for sikorsky due primarily to intangible amortization and adjustments required to account for the acquisition of this business in the fourth quarter of 2015 ; and approximately $ 15 million for integrated warfare systems and sensors programs , primarily due to investments made in connection with a recently awarded next generation radar technology program , partially offset by higher risk retirements ( including halifax class modernization ) . these decreases were partially offset by approximately $ 20 million in increased operating profit for training and logistics services programs , primarily due to reserves recorded on certain programs in 2014 that were not repeated in 2015 . adjustments not related to volume , including net profit booking rate adjustments and other matters , were approximately $ 100 million lower in 2015 compared to 2014. .