table of contents other equity method investments infraservs . we hold indirect ownership interests in several german infraserv groups that own and develop industrial parks and provide on-site general and administrative support to tenants . our ownership interest in the equity investments in infraserv affiliates are as follows : as of december 31 , 2017 ( in percentages ) infraserv gmbh & co . gendorf kg ( 1 ) ................................................................................................... . 39 .

Table:
 | as of december 31 2017 ( in percentages )
infraserv gmbh & co . gendorf kg ( 1 ) | 39
infraserv gmbh & co . hoechst kg | 32
infraserv gmbh & co . knapsack kg ( 1 ) | 27
infraserv gmbh & co .
knapsack kg ( 1 ) ................................................................................................ .
27 ______________________________ ( 1 ) see note 29 - subsequent events in the accompanying consolidated financial statements for further information .
research and development our business models leverage innovation and conduct research and development activities to develop new , and optimize existing , production technologies , as well as to develop commercially viable new products and applications .
research and development expense was $ 72 million , $ 78 million and $ 119 million for the years ended december 31 , 2017 , 2016 and 2015 , respectively .
we consider the amounts spent during each of the last three fiscal years on research and development activities to be sufficient to execute our current strategic initiatives .
intellectual property we attach importance to protecting our intellectual property , including safeguarding our confidential information and through our patents , trademarks and copyrights , in order to preserve our investment in research and development , manufacturing and marketing .
patents may cover processes , equipment , products , intermediate products and product uses .
we also seek to register trademarks as a means of protecting the brand names of our company and products .
patents .
in most industrial countries , patent protection exists for new substances and formulations , as well as for certain unique applications and production processes .
however , we do business in regions of the world where intellectual property protection may be limited and difficult to enforce .
confidential information .
we maintain stringent information security policies and procedures wherever we do business .
such information security policies and procedures include data encryption , controls over the disclosure and safekeeping of confidential information and trade secrets , as well as employee awareness training .
trademarks .
amcel ae , aoplus ae , ateva ae , avicor ae , celanese ae , celanex ae , celcon ae , celfx ae , celstran ae , celvolit ae , clarifoil ae , dur- o-set ae , ecomid ae , ecovae ae , forflex ae , forprene ae , frianyl ae , fortron ae , ghr ae , gumfit ae , gur ae , hostaform ae , laprene ae , metalx ae , mowilith ae , mt ae , nilamid ae , nivionplast ae , nutrinova ae , nylfor ae , pibiflex ae , pibifor ae , pibiter ae , polifor ae , resyn ae , riteflex ae , slidex ae , sofprene ae , sofpur ae , sunett ae , talcoprene ae , tecnoprene ae , thermx ae , tufcor ae , vantage ae , vectra ae , vinac ae , vinamul ae , vitaldose ae , zenite ae and certain other branded products and services named in this document are registered or reserved trademarks or service marks owned or licensed by celanese .
the foregoing is not intended to be an exhaustive or comprehensive list of all registered or reserved trademarks and service marks owned or licensed by celanese .
fortron ae is a registered trademark of fortron industries llc .
hostaform ae is a registered trademark of hoechst gmbh .
mowilith ae and nilamid ae are registered trademarks of celanese in most european countries .
we monitor competitive developments and defend against infringements on our intellectual property rights .
neither celanese nor any particular business segment is materially dependent upon any one patent , trademark , copyright or trade secret .
environmental and other regulation matters pertaining to environmental and other regulations are discussed in item 1a .
risk factors , as well as note 2 - summary of accounting policies , note 16 - environmental and note 24 - commitments and contingencies in the accompanying consolidated financial statements. .

Question: what is the percentage change in research and development expense from 2015 to 2016?
Answer: -34.5%
Calculation: subtract(78, 119), divide(#0, 119)