24 Average number of employees and personnel costs (XLS:) Download 2018 2017 2016 GROUP (TOTAL) 216,369 216,454 220,582 Domestic 100,227 103,174 107,793 International 116,142 113,280 112,790 Non-civil servants 202,010 200,673 203,110 Civil servants (domestic, active service relationship) 14,359 15,781 17,472 Trainees and students on cooperative degree courses 5,713 6,559 7,510 PERSONNEL COSTS millions of € 16,436 15,504 16,463 Average headcount essentially remained unchanged year-on-year. It slightly decreased in Germany by 2.9 percent. Staff restructuring measures in the Germany operating segment and in the German part of the Group Headquarters & Group Services segment in particular contributed to this trend. The average headcount outside Germany grew by 2.5 percent, with moderate increases in the United States and Europe (primarily due to the first-time consolidation of UPC Austria) operating segments, as well as in the number of employees assigned to countries other than Germany in the Group Headquarters & Group Services segment. Personnel costs increased by 6.0 percent year-on-year, due to restructuring expenses in connection with the early retirement arrangements for civil servants and increases in salaries under collective agreements concluded in 2018. The main collective agreements were concluded between Deutsche Telekom and union representatives on April 12, 2018 and apply with retroactive effect as of February 1, 2018 for a term of 26 months. By contrast, decreases in headcount in Germany had a decreasing effect on personnel costs.