performance and revenue growth depends , in part , on the reliability and functionality of this infrastructure as a means of delivering human resources services . the internet is a key mechanism for delivering our human resources services to our hr solutions clients efficiently and cost effectively . our clients may not be receptive to human resource services delivered over the internet due to concerns regarding transaction security , user privacy , the reliability and quality of internet service and other reasons . our clients 2019 concerns may be heightened by the fact we use the internet to transmit extremely confidential information about our clients and their employees , such as compensation , medical information and other personally identifiable information . in order to maintain the level of security , service and reliability that our clients require , we may be required to make significant investments in our online methods of delivering human resources services . in addition , websites and proprietary online services have experienced service interruptions and other delays occurring throughout their infrastructure . the adoption of additional laws or regulations with respect to the internet may impede the efficiency of the internet as a medium of exchange of information and decrease the demand for our services . if we cannot use the internet effectively to deliver our services , our revenue growth and results of operation may be impaired . we may lose client data as a result of major catastrophes and other similar problems that may materially adversely impact our operations . we have multiple processing centers around the world that use various commercial methods for disaster recovery capabilities . our main data processing center is located near the aon hewitt headquarters in lincolnshire , illinois . in the event of a disaster , our business continuity may not be sufficient , and the data recovered may not be sufficient for the administration of our clients 2019 human resources programs and processes . 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 200 e . randolph street in chicago , illinois , where we occupy approximately 327000 square feet of space under an operating lease agreement that expires in 2013 . there are two five-year renewal options at current market rates . we own one 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. .

Table: property: occupied square footage lease expiration dates 4 overlook point and other locations lincolnshire illinois 1279000 2014 - 2019 2601 research forest drive the woodlands texas 414000 2020 2300 discovery drive orlando florida 364000 2020 devonshire square and other locations london uk 339000 2018 - 2028 199 water street new york new york 337000 2018 1000 n . milwaukee avenue glenview illinois 233000 2017 7201 hewitt associates drive charlotte north carolina 218000 2015

7201 hewitt associates drive , charlotte , north carolina . . . . . . . . . . . . . . . . . . . . . . . . . . . . 218000 2015 the locations in lincolnshire , illinois , the woodlands , texas , orlando , florida , and charlotte north carolina , each of which were acquired as part of the hewitt acquisition , are primarily dedicated to our hr solutions business . the other locations listed above house personnel from each of our business segments. .

Question: from the data given , how many square feet have an expiry date in 2020?
Answer: 778000
Calculation: add(414000, 364000)