Please answer the given financial question based on the context.
Context: 2016 vs . 2015 sales of $ 498.8 increased $ 212.1 , or 74% ( 74 % ) . the increase in sales was driven by the jazan project which more than offset the decrease in small equipment and other air separation unit sales . in 2016 , we recognized approximately $ 300 of sales related to the jazan project . operating loss of $ 21.3 decreased 59% ( 59 % ) , or $ 30.3 , primarily from income on the jazan project and benefits from cost reduction actions , partially offset by lower other sale of equipment project activity and a gain associated with the cancellation of a sale of equipment contract that was recorded in fiscal year 2015 . corporate and other the corporate and other segment includes two ongoing global businesses ( our lng equipment business and our liquid helium and liquid hydrogen transport and storage container businesses ) , and corporate support functions that benefit all the segments . corporate and other also includes income and expense that is not directly associated with the business segments , including foreign exchange gains and losses and stranded costs . stranded costs result from functional support previously provided to the two divisions comprising the former materials technologies segment . the majority of these costs are reimbursed to air products pursuant to short-term transition services agreements under which air products provides transition services to versum for emd and to evonik for pmd . the reimbursement for costs in support of the transition services has been reflected on the consolidated income statements within "other income ( expense ) , net." .
||2017|2016|2015|
|sales|$ 82.6|$ 236.0|$ 315.4|
|operating loss|-170.6 ( 170.6 )|-87.6 ( 87.6 )|-86.5 ( 86.5 )|
|adjusted ebitda|-158.4 ( 158.4 )|-68.1 ( 68.1 )|-66.2 ( 66.2 )|
2017 vs . 2016 sales of $ 82.6 decreased $ 153.4 , primarily due to lower lng project activity . we expect continued weakness in new lng project orders due to continued oversupply of lng in the market . operating loss of $ 170.6 increased $ 83.0 due to lower lng activity , partially offset by productivity improvements and income from transition service agreements with versum and evonik . 2016 vs . 2015 sales of $ 236.0 decreased $ 79.4 , or 25% ( 25 % ) , primarily due to lower lng sale of equipment activity . operating loss of $ 87.6 increased 1% ( 1 % ) , or $ 1.1 , due to lower lng activity , mostly offset by benefits from our recent cost reduction actions and lower foreign exchange losses . reconciliation of non-gaap financial measures ( millions of dollars unless otherwise indicated , except for per share data ) the company has presented certain financial measures on a non-gaap ( 201cadjusted 201d ) basis and has provided a reconciliation to the most directly comparable financial measure calculated in accordance with gaap . these financial measures are not meant to be considered in isolation or as a substitute for the most directly comparable financial measure calculated in accordance with gaap . the company believes these non-gaap measures provide investors , potential investors , securities analysts , and others with useful supplemental information to evaluate the performance of the business because such measures , when viewed together with our financial results computed in accordance with gaap , provide a more complete understanding of the factors and trends affecting our historical financial performance and projected future results . in many cases , our non-gaap measures are determined by adjusting the most directly comparable gaap financial measure to exclude certain disclosed items ( 201cnon-gaap adjustments 201d ) that we believe are not representative of the underlying business performance . for example , air products has executed its strategic plan to restructure the company to focus on its core industrial gases business . this resulted in significant cost reduction and asset actions that we believe are important for investors to understand separately from the performance of the underlying business . the reader should be aware that we may incur similar expenses in the future . the tax impact of our non- gaap adjustments reflects the expected current and deferred income tax expense impact of the transactions and is impacted primarily by the statutory tax rate of the various relevant jurisdictions and the taxability of the adjustments in those jurisdictions . investors should also consider the limitations associated with these non-gaap measures , including the potential lack of comparability of these measures from one company to another. .
Question: considering the years 2015-2017 , what is the highest adjusted ebitda observed?
Answer:
-66.2