in madison wi what was the ratio of the square feet excluded for which the leases do not commence until 2018 as of december 31 , 2017
table of contents item 2 . properties . the following table summarizes the facilities we lease as of december 31 , 2017 , including the location and size of each principal facility , and their designated use . we believe our facilities are adequate for our current and near-term needs , and will be able to locate additional facilities as needed . location approximate square feet operation expiration dates .

| Location | Approximate Square Feet | Operation | LeaseExpiration Dates |
| :--- | :--- | :--- | :--- |
| San Diego, CA | 1,218,000 | R&D, Manufacturing, Warehouse, Distribution, and Administrative | 2018 – 2031 |
| San Francisco Bay Area, CA | 616,000 | R&D, Manufacturing, Warehouse, and Administrative | 2018 – 2025 |
| Singapore | 395,000 | R&D, Manufacturing, Warehouse, Distribution, and Administrative | 2018 – 2025 |
| Cambridge, United Kingdom* | 92,000 | R&D, Manufacturing, and Administrative | 2020 – 2024 |
| Eindhoven, the Netherlands | 42,000 | Distribution and Administrative | 2020 |
| Madison, WI* | 73,000 | R&D, Manufacturing, Warehouse, Distribution, and Administrative | 2018 – 2019 |
| Other* | 78,000 | Administrative | 2018 – 2022 |

________________ *excludes approximately 309000 square feet for which the leases do not commence until 2018 and beyond . item 3 . legal proceedings . we are involved in various lawsuits and claims arising in the ordinary course of business , including actions with respect to intellectual property , employment , and contractual matters . in connection with these matters , we assess , on a regular basis , the probability and range of possible loss based on the developments in these matters . a liability is recorded in the financial statements if it is believed to be probable that a loss has been incurred and the amount of the loss can be reasonably estimated . because litigation is inherently unpredictable and unfavorable results could occur , assessing contingencies is highly subjective and requires judgments about future events . we regularly review outstanding legal matters to determine the adequacy of the liabilities accrued and related disclosures . the amount of ultimate loss may differ from these estimates . each matter presents its own unique circumstances , and prior litigation does not necessarily provide a reliable basis on which to predict the outcome , or range of outcomes , in any individual proceeding . because of the uncertainties related to the occurrence , amount , and range of loss on any pending litigation or claim , we are currently unable to predict their ultimate outcome , and , with respect to any pending litigation or claim where no liability has been accrued , to make a meaningful estimate of the reasonably possible loss or range of loss that could result from an unfavorable outcome . in the event opposing litigants in outstanding litigations or claims ultimately succeed at trial and any subsequent appeals on their claims , any potential loss or charges in excess of any established accruals , individually or in the aggregate , could have a material adverse effect on our business , financial condition , results of operations , and/or cash flows in the period in which the unfavorable outcome occurs or becomes probable , and potentially in future periods . item 4 . mine safety disclosures . not applicable. .

square_feet_excluded = 309000
square_feet_total = 73000
ratio_square_feet_excluded = square_feet_excluded / square_feet_total
answer = ratio_square_feet_excluded