additionally , the latin american soft alloy extrusions business previously included in corporate was moved into the new transportation and construction solutions segment . the remaining engineered products and solutions segment consists of the alcoa fastening systems and rings ( renamed to include portions of the firth rixson business acquired in november 2014 ) , alcoa power and propulsion ( includes the tital business acquired in march 2015 ) , alcoa forgings and extrusions ( includes the other portions of firth rixson ) , and alcoa titanium and engineered products ( a new business unit that consists solely of the rti international metals business acquired in july 2015 ) business units . segment information for all prior periods presented was updated to reflect the new segment structure . atoi for all reportable segments totaled $ 1906 in 2015 , $ 1968 in 2014 , and $ 1267 in 2013 . the following information provides shipments , sales , and atoi data for each reportable segment , as well as certain production , realized price , and average cost data , for each of the three years in the period ended december 31 , 2015 . see note q to the consolidated financial statements in part ii item 8 of this form 10-k for additional information . alumina .

Table: 2015 2014 2013 alumina production ( kmt ) 15720 16606 16618 third-party alumina shipments ( kmt ) 10755 10652 9966 alcoa 2019s average realized price per metric ton of alumina $ 317 $ 324 $ 328 alcoa 2019s average cost per metric ton of alumina* $ 237 $ 282 $ 295 third-party sales $ 3455 $ 3509 $ 3326 intersegment sales 1687 1941 2235 total sales $ 5142 $ 5450 $ 5561 atoi $ 746 $ 370 $ 259

* includes all production-related costs , including raw materials consumed ; conversion costs , such as labor , materials , and utilities ; depreciation , depletion , and amortization ; and plant administrative expenses . this segment represents a portion of alcoa 2019s upstream operations and consists of the company 2019s worldwide refining system . alumina mines bauxite , from which alumina is produced and then sold directly to external smelter customers , as well as to the primary metals segment ( see primary metals below ) , or to customers who process it into industrial chemical products . more than half of alumina 2019s production is sold under supply contracts to third parties worldwide , while the remainder is used internally by the primary metals segment . alumina produced by this segment and used internally is transferred to the primary metals segment at prevailing market prices . a portion of this segment 2019s third- party sales are completed through the use of agents , alumina traders , and distributors . generally , the sales of this segment are transacted in u.s . dollars while costs and expenses of this segment are transacted in the local currency of the respective operations , which are the australian dollar , the brazilian real , the u.s . dollar , and the euro . awac is an unincorporated global joint venture between alcoa and alumina limited and consists of a number of affiliated operating entities , which own , or have an interest in , or operate the bauxite mines and alumina refineries within the alumina segment ( except for the poc 0327os de caldas refinery in brazil and a portion of the sa 0303o lul 0301s refinery in brazil ) . alcoa owns 60% ( 60 % ) and alumina limited owns 40% ( 40 % ) of these individual entities , which are consolidated by the company for financial reporting purposes . as such , the results and analysis presented for the alumina segment are inclusive of alumina limited 2019s 40% ( 40 % ) interest . in december 2014 , awac completed the sale of its ownership stake in jamalco , a bauxite mine and alumina refinery joint venture in jamaica , to noble group ltd . jamalco was 55% ( 55 % ) owned by a subsidiary of awac , and , while owned by awac , 55% ( 55 % ) of both the operating results and assets and liabilities of this joint venture were included in the alumina segment . as it relates to awac 2019s previous 55% ( 55 % ) ownership stake , the refinery ( awac 2019s share of the capacity was 779 kmt-per-year ) generated sales ( third-party and intersegment ) of approximately $ 200 in 2013 , and the refinery and mine combined , at the time of divestiture , had approximately 500 employees . see restructuring and other charges in results of operations above. .

Question: what is the percentual reduction of intersegment sales concerning the total sales during 2013 and 2014?
Answer: 4.58%
Calculation: subtract(divide(2235, 5561), divide(1941, 5450))
Explanation: it is the difference between the percentage of intersegment sales concerning total sales in 2013 ( 40.19% ) and 2014 ( 35.61% )