13. Intangible non-current assets (in millions of euros)GoodwillSoftware and concessionsTotalComposition per 1 January 2015 Cost37209246Cumulative depreciation and impairment56772Carrying amount as at 1 January 201532142174 Changes in 2015 Additions- 6565Depreciation- -36-36Divestments- - - Impairment- - - Reversal impairment- - - Other changes11919Total changes14848 Composition per 31 December 2015 Cost38361404Cumulative depreciation and impairment5169179Carrying amount as at 31 December 201533192225 Changes in 2016 Additions- 8686Depreciation- -40-40Divestments- - - Impairments- - - Reversal impairment- - - Other changes-13-1-14Total changes-134532 Composition per 31 December 2016 Cost20469489Cumulative depreciation and impairment- 232232Carrying amount as at 31 December 201620237257The other changes in 2016 mainly due to the transfer of goodwill to assets held for sale. The remaining goodwill relates to our operations in the UK and Germany.The cash flows that were used for determining the impairments are based on the business plans drawn up by the business unit concerned for a period of at least five years. A weighted average discount rate is determined for each cash-generating unit, in line with those for comparable companies. The calculations that give the impairments and their reversals are based on a weighted average post-tax discount rate that is between 5.5% and 7% (2015: between 5.5% and 7%). Changes in the assumptions did not lead to a deviation from the amounts calculated.