.6% ( 1.6 % ) ) , due primarily to lower shipment volume ( $ 1046 million ) , partially offset by higher pricing . operating companies income increased $ 824 million ( 13.2% ( 13.2 % ) ) , due primarily to higher pricing ( $ 765 million ) , npm adjustment items ( $ 664 million ) and lower marketing , administration and research costs , partially offset by lower shipment volume ( $ 512 million ) , and higher per unit settlement charges