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: .
[['2017', '$ 942'], ['2018', '525'], ['2019', '307'], ['2020', '298'], ['2021', '276'], ['thereafter', '2983'], ['total', '$ 5331']]
approximately $ 4000 of our unconditional purchase obligations relate to helium purchases , which include crude feedstock supply to multiple helium refining plants in north america as well as refined helium purchases from sources around the world .as a rare byproduct of natural gas production in the energy sector , these helium sourcing agreements are medium- to long-term and contain take-or-pay provisions .the refined helium is distributed globally and sold as a merchant gas , primarily under medium-term requirements contracts .while contract terms in the energy sector are longer than those in merchant , helium is a rare gas used in applications with few or no substitutions because of its unique physical and chemical properties .approximately $ 330 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 $ 350 for additional plant and equipment are included in the unconditional purchase obligations in 2017 .in addition , we have purchase commitments totaling approximately $ 500 in 2017 and 2018 relating to our long-term sale of equipment project for saudi aramco 2019s jazan oil refinery .18 .capital stock common stock authorized common stock consists of 300 million shares with a par value of $ 1 per share .as of 30 september 2016 , 249 million shares were issued , with 217 million outstanding .on 15 september 2011 , the board of directors authorized the repurchase of up to $ 1000 of our outstanding common stock .we repurchase shares pursuant to rules 10b5-1 and 10b-18 under the securities exchange act of 1934 , as amended , through repurchase agreements established with several brokers .we did not purchase any of our outstanding shares during fiscal year 2016 .at 30 september 2016 , $ 485.3 in share repurchase authorization remains. .

Question: what is the percentage of outstanding shares among all issued shares?
Answer: 87.14%
Explanation: it is the number of outstanding shares divided by the number of shares issued in total , then turned into a percentage .