20 Net revenue Net revenue breaks down into the following revenue categories: (XLS:) Download millions of € 2019 2018b 2017b a Revenue from the sale of goods and merchandise includes interest income of EUR 345 million in the reporting year, calculated using the effective interest method (2018: EUR 305 million). This income is primarily attributable to accrued interest on receivables in connection with handsets sold under installment plans in the United States operating segment. b Prior-year figures were adjusted retrospectively on account of a change in the allocation between revenue categories. This change relates to revenue from the use of entity assets by others of EUR 290 million in 2018 and of EUR 307 million in 2017 in the Group Development operating segment that had been reported under revenue from the rendering of services in the 2018 Annual Report. Revenue from the rendering of services 65,489 61,653 62,141 Germany 17,445 17,657 18,382 United States 31,313 27,755 27,232 Europe 10,023 9,883 9,937 Systems Solutions 5,149 5,328 5,413 Group Development 1,487 967 1,067 Group Headquarters & Group Services 71 63 110 Revenue from the sale of goods and merchandisea 12,960 12,443 11,079 Germany 2,298 2,208 1,735 United States 8,569 8,170 7,714 Europe 1,556 1,588 1,236 Systems Solutions 143 154 90 Group Development 394 322 286 Group Headquarters & Group Services 0 0 18 Revenue from the use of entity assets by others 2,081 1,561 1,727 Germany 829 486 436 United States 536 596 789 Europe 229 51 45 Systems Solutions 88 15 0 Group Development 276 290 307 Group Headquarters & Group Services 124 123 150 NET REVENUE 80,531 75,656 74,947 Net revenue for the reporting year was EUR 80.5 billion, up EUR 4.9 billion on the prior-year level. For information on changes in net revenue, please refer to the section “Development of business in the Group” in the combined management report. The total transaction price attributable to performance obligations that have not been fulfilled or, in some cases, not yet fulfilled at the end of the reporting year (hereinafter: outstanding transaction price) amounts to EUR 19,059 million (2018: EUR 18,323 million). The portion of the outstanding transaction price attributable to performance obligations that have not been fulfilled or, in some cases, not yet fulfilled at the end of the reporting year is generally recognized as revenue over the remaining term of the service contracts concluded. Since most service contracts – unless they can be canceled at any time – have a minimum contract term of 24 months, an average remaining term of approximately 12 months can be assumed, provided the course of business in the mass business remains virtually unchanged. The disclosures only refer to transactions within the scope of IFRS 15, i.e., they do not include portions of the transaction price being allocated to performance obligations outside the scope of the standard, e.g., leases. Deutsche Telekom generally makes use of the practical expedients in IFRS 15, according to which outstanding performance obligations under contracts with an expected original term of no more than one year and revenues recognized in accordance with the billed amounts are exempt from the disclosure requirement. Individual subsidiaries deviate from this general approach and have not made use of these practical expedients for similar contracts. Service concession arrangements Satellic NV, Machelen, Belgium, is a fully consolidated subsidiary of Deutsche Telekom and on July 25, 2014 signed a contractual arrangement with Viapass, the public agency responsible for toll collection in Belgium, for the set-up, operation, and financing of an electronic toll collection system. After Viapass accepted the system on March 30, 2016, the set-up phase was completed on March 31, 2016. The operation phase that follows will have a duration of twelve years, with the additional option for Viapass to extend the term three times by one year. Satellic has no entitlement to the toll revenue collected but will receive contractually agreed fees for setting up and operating the system. Viapass is authorized to terminate the arrangement giving notice of six months with payment of reasonable compensation. In the event of regular or premature termination of the agreement, Satellic has an obligation to hand over to Viapass, on request, material assets for the operation of the toll collection system that have not yet passed to the ownership of Viapass; in such an event, however, the software platform for toll collection would not be handed over to Viapass. The agreement was classified as a service concession arrangement within the meaning of IFRIC 12. Since the start of the operation phase on April 1, 2016, the separate fees for operation and maintenance services have been recognized as revenue in the respective periods, which totaled EUR 66 million in the reporting year (2018: EUR 67 million, 2017: EUR 75 million).