Financial report context:
( 2 ) in 2013 , our principal u.k subsidiary agreed with the trustees of one of the u.k . plans to contribute an average of $ 11 million per year to that pension plan for the next three years . the trustees of the plan have certain rights to request that our u.k . subsidiary advance an amount equal to an actuarially determined winding-up deficit . as of december 31 , 2015 , the estimated winding-up deficit was a3240 million ( $ 360 million at december 31 , 2015 exchange rates ) . the trustees of the plan have accepted in practice the agreed-upon schedule of contributions detailed above and have not requested the winding-up deficit be paid . ( 3 ) purchase obligations are defined as agreements to purchase goods and services that are enforceable and legally binding on us , and that specifies all significant terms , including what is to be purchased , at what price and the approximate timing of the transaction . most of our purchase obligations are related to purchases of information technology services or other service contracts . ( 4 ) excludes $ 12 million of unfunded commitments related to an investment in a limited partnership due to our inability to reasonably estimate the period ( s ) when the limited partnership will request funding . ( 5 ) excludes $ 218 million of liabilities for uncertain tax positions due to our inability to reasonably estimate the period ( s ) when potential cash settlements will be made . financial condition at december 31 , 2015 , our net assets were $ 6.2 billion , representing total assets minus total liabilities , a decrease from $ 6.6 billion at december 31 , 2014 . the decrease was due primarily to share repurchases of $ 1.6 billion , dividends of $ 323 million , and an increase in accumulated other comprehensive loss of $ 289 million related primarily to an increase in the post- retirement benefit obligation , partially offset by net income of $ 1.4 billion for the year ended december 31 , 2015 . working capital increased by $ 77 million from $ 809 million at december 31 , 2014 to $ 886 million at december 31 , 2015 . accumulated other comprehensive loss increased $ 289 million at december 31 , 2015 as compared to december 31 , 2014 , which was primarily driven by the following : 2022 negative net foreign currency translation adjustments of $ 436 million , which are attributable to the strengthening of the u.s . dollar against certain foreign currencies , 2022 a decrease of $ 155 million in net post-retirement benefit obligations , and 2022 net financial instrument losses of $ 8 million . review by segment general we serve clients through the following segments : 2022 risk solutions acts as an advisor and insurance and reinsurance broker , helping clients manage their risks , via consultation , as well as negotiation and placement of insurance risk with insurance carriers through our global distribution network . 2022 hr solutions partners with organizations to solve their most complex benefits , talent and related financial challenges , and improve business performance by designing , implementing , communicating and administering a wide range of human capital , retirement , investment management , health care , compensation and talent management strategies . risk solutions .

Financial table:
years ended december 31 ( millions except percentage data ): revenue; 2015: $ 7426; 2014: $ 7834; 2013: $ 7789
years ended december 31 ( millions except percentage data ): operating income; 2015: 1506; 2014: 1648; 2013: 1540
years ended december 31 ( millions except percentage data ): operating margin; 2015: 20.3% ( 20.3 % ); 2014: 21.0% ( 21.0 % ); 2013: 19.8% ( 19.8 % )

Additional report context:
the demand for property and casualty insurance generally rises as the overall level of economic activity increases and generally falls as such activity decreases , affecting both the commissions and fees generated by our brokerage business . the economic activity that impacts property and casualty insurance is described as exposure units , and is most closely correlated .

Question: what is the net income margin for 2015?
Answer: 18.9%