approximately 99% ( 99 % ) of the outstanding shares of common stock of aon corporation were held within the dtc system . the class a ordinary shares of aon plc are , at present , eligible for deposit and clearing within the dtc system . in connection with the closing of the redomestication , we entered into arrangements with dtc whereby we agreed to indemnify dtc for any stamp duty and/or sdrt that may be assessed upon it as a result of its service as a depository and clearing agency for our class a ordinary shares . in addition , we have obtained a ruling from hmrc in respect of the stamp duty and sdrt consequences of the reorganization , and sdrt has been paid in accordance with the terms of this ruling in respect of the deposit of class a ordinary shares with the initial depository . dtc will generally have discretion to cease to act as a depository and clearing agency for the class a ordinary shares . if dtc determines at any time that the class a ordinary shares are not eligible for continued deposit and clearance within its facilities , then we believe the class a ordinary shares would not be eligible for continued listing on a u.s . securities exchange or inclusion in the s&p 500 and trading in the class a ordinary shares would be disrupted . while we would pursue alternative arrangements to preserve our listing and maintain trading , any such disruption could have a material adverse effect on the trading price of the class a ordinary shares . item 1b . unresolved staff comments . item 2 . properties . we have offices in various locations throughout the world . substantially all of our offices are located in leased premises . we maintain our corporate headquarters at 122 leadenhall street , london , england , where we occupy approximately 190000 square feet of space under an operating lease agreement that expires in 2034 . we own one significant building at pallbergweg 2-4 , amsterdam , the netherlands ( 150000 square feet ) . the following are additional significant leased properties , along with the occupied square footage and expiration . property : occupied square footage expiration .

Table: property: occupiedsquare footage leaseexpiration dates 4 overlook point and other locations lincolnshire illinois 1059000 2019 2013 2024 tikri campus and unitech cyber park gurgaon india 440000 2015 2013 2019 200 e . randolph street chicago illinois 428000 2028 2601 research forest drive the woodlands texas 414000 2020 2300 discovery drive orlando florida 364000 2020 199 water street new york new york 319000 2018 7201 hewitt associates drive charlotte north carolina 218000 2025

the locations in lincolnshire , illinois , gurgaon , india , the woodlands , texas , orlando , florida , and charlotte , north carolina , are primarily dedicated to our hr solutions segment . the other locations listed above house personnel from both of our reportable segments . in general , no difficulty is anticipated in negotiating renewals as leases expire or in finding other satisfactory space if the premises become unavailable . we believe that the facilities we currently occupy are adequate for the purposes for which they are being used and are well maintained . in certain circumstances , we may have unused space and may seek to sublet such space to third parties , depending upon the demands for office space in the locations involved . see note 7 "lease commitments" of the notes to consolidated financial statements in part ii , item 8 of this report for information with respect to our lease commitments as of december 31 , 2015 . item 3 . legal proceedings . we hereby incorporate by reference note 14 "commitments and contingencies" of the notes to consolidated financial statements in part ii , item 8 of this report . item 4 . mine safety disclosure . not applicable. .

Question: how many years are left till the lease expiration date for the building of aon's corporate headquarters?
Answer: 19
Calculation: subtract(2034, 2015)