220/264 Notes to the 2017 consolidated financial statements Revenue by country 2015 2016 2017 (in € millions) United States 741 1,173 1,577 United Kingdom 268 342 444 Luxembourg 1 1 3 Other countries 930 1,436 2,066 1,940 2,952 4,090 Premium revenues are attributed to a country based on where the membership originates. Advertising revenues are attributed to a country based on where the campaign is viewed. There are no countries that make up greater than 10% of total revenue included in “Other countries”. Non­current assets by country Non­current assets for this purpose consists of property and equipment. 2016 2017 (in € millions) Sweden 12 32 United States 50 28 United Kingdom 19 6 Other countries 4 7 85 73 As of December 31, 2016 and 2017, the Group held no property and equipment in Luxembourg. 7. Personnel expenses 2015 2016 2017 (in € millions, except employee data) Wages and salaries 163 231 348 Social costs 45 38 136 Contributions to retirement plans 7 12 17 Share­based payments 28 53 65 Other employee benefits 16 39 48 259 373 614 Average full­time employees 1,534 2,084 2,960 8. Auditor remuneration 2015 2016 2017 (in € millions) Audit and audit related fees 3 4 5 F­27