Segment Information The results of the reportable segments are derived directly from our management reporting system and are based on our methods of internal reporting which are not necessarily in conformity with GAAP. Management measures the performance of each segment based on several metrics, including contribution margin, as defined below. Management does not use asset information to assess performance and make decisions regarding allocation of resources. Therefore, depreciation and amortization expense are not allocated among segments. Contribution margin is used, in part, to evaluate the performance of, and allocate resources to, each of the segments. Segment contribution margin includes segment revenue less the related cost of sales excluding certain operating expenses that are not allocated to segments because they are separately managed at the consolidated corporate level. These unallocated costs include stock-based compensation expense, amortization of certain acquired intangible assets, direct sales and marketing costs, research and development costs, corporate general and administrative costs, such as legal and accounting, interest income, interest expense, and other income and expense. Financial information for each reportable segment was as follows (in thousands): Years Ended January 31, 2019 2018 (As Adjusted)* 2017 (As Adjusted)* Revenue: Subscription $ 406,333 $ 302,617 $ 208,335 Services 73,608 69,676 64,208 Total revenue $ 479,941 $ 372,293 $ 272,543 * As adjusted to reflect the impact of the full retrospective adoption of Topic 606. See Note 2 for a summary of adjustments. Years Ended January 31, 2019 2018 (As Adjusted)* 2017 (As Adjusted)* Contribution margin: Subscription $ 356,214 $ 258,771 $ 173,054 Services 12,315 14,386 17,727 Total segment contribution margin $ 368,529 $ 273,157 $ 190,781 * As adjusted to reflect the impact of the full retrospective adoption of Topic 606. See Note 2 for a summary of adjustments. The reconciliation of segment financial information to our loss from operations is as follows (in thousands): Years Ended January 31, 2019 2018 (As Adjusted)* 2017 (As Adjusted)* Segment contribution margin $ 368,529 $ 273,157 $ 190,781 Amortization of acquired intangible assets (9,129 ) (3,723 ) (3,720 ) Stock-based compensation expense (117,365 ) (290,006 ) (21,714 ) Donation of common stock to the Cloudera Foundation   (21,574 ) Corporate costs, such as research and development, corporate general and administrative and other (435,799 ) (353,600 ) (301,855 ) Loss from operations $ (193,764 ) $ (374,172 ) $ (158,082 ) * As adjusted to reflect the impact of the full retrospective adoption of Topic 606. See Note 2 for a summary of adjustments. Sales outside of the United States represented approximately 34% , 30% and 27% of our total revenue for the years ended January 31, 2019 , 2018 and 2017 , respectively. No individual foreign country represented more than 10% of revenue in any period presented. All revenues from external customers are attributed to individual countries on an end-customer basis, based on domicile of the purchasing entity, if known, or the location of the customers headquarters if the specific purchasing entity within the customer is unknown. As of January 31, 2019 and 2018 , assets located outside the United States were 4% of total assets