guarantees and warranties in april 2015 , we entered into joint venture arrangements in saudi arabia . an equity bridge loan has been provided to the joint venture until 2020 to fund equity commitments , and we guaranteed the repayment of our 25% ( 25 % ) share of this loan . our venture partner guaranteed repayment of their share . our maximum exposure under the guarantee is approximately $ 100 . as of 30 september 2015 , we recorded a noncurrent liability of $ 67.5 for our obligation to make future equity contributions based on the equity bridge loan . air products has also entered into a sale of equipment contract with the joint venture to engineer , procure , and construct the industrial gas facilities that will supply gases to saudi aramco . we will provide bank guarantees to the joint venture of up to $ 326 to support our performance under the contract . we are party to an equity support agreement and operations guarantee related to an air separation facility constructed in trinidad for a venture in which we own 50% ( 50 % ) . at 30 september 2015 , maximum potential payments under joint and several guarantees were $ 30.0 . exposures under the guarantee decline over time and will be completely extinguished by 2024 . during the first quarter of 2014 , we sold the remaining portion of our homecare business and entered into an operations guarantee related to obligations under certain homecare contracts assigned in connection with the transaction . our maximum potential payment under the guarantee is a320 million ( approximately $ 30 at 30 september 2015 ) , and our exposure will be extinguished by 2020 . to date , no equity contributions or payments have been made since the inception of these guarantees . the fair value of the above guarantees is not material . we , in the normal course of business operations , have issued product warranties related to equipment sales . also , contracts often contain standard terms and conditions which typically include a warranty and indemnification to the buyer that the goods and services purchased do not infringe on third-party intellectual property rights . the provision for estimated future costs relating to warranties is not material to the consolidated financial statements . we do not expect that any sum we may have to pay in connection with guarantees and warranties will have a material adverse effect on our consolidated financial condition , liquidity , or results of operations . unconditional purchase obligations we are obligated to make future payments under unconditional purchase obligations as summarized below: .

$ 917: 2017: 117
2018: 63
2019: 55
2020: 54
thereafter: 164
total: 1370

approximately $ 390 of our long-term unconditional purchase obligations relate to feedstock supply for numerous hyco ( hydrogen , carbon monoxide , and syngas ) facilities . the price of feedstock supply is principally related to the price of natural gas . however , long-term take-or-pay sales contracts to hyco customers are generally matched to the term of the feedstock supply obligations and provide recovery of price increases in the feedstock supply . due to the matching of most long-term feedstock supply obligations to customer sales contracts , we do not believe these purchase obligations would have a material effect on our financial condition or results of operations . the unconditional purchase obligations also include other product supply and purchase commitments and electric power and natural gas supply purchase obligations , which are primarily pass-through contracts with our customers . purchase commitments to spend approximately $ 540 for additional plant and equipment are included in the unconditional purchase obligations in 2016. .

Questions:
what was the total of unconditional purchase obligations in 2017?
and what was it in 2016?
what was, then, the change in unconditional purchase obligations over the year?
and how much does this change represent in relation to the 2016 total?

Answers:
117
917
-800
-87.24%