13 Other provisions

millions of €
  Provisions for termination benefits Other provisions for personnel costs Provisions for restoration obligations Provisions for litigation risks Provisions for sales and procurement support Miscellaneous other provisions Total
At December 31, 2015 186 2,263 1,546 314 460 1,576 6,345
Of which: current 183 1,452 66 307 460 899 3,367
Changes in the composition of the Group (4) 0 0 0 0 (1) (5)
Currency translation adjustments 0 21 16 1 4 6 48
Addition 62 1,892 327 64 470 417 3,232
Use (45) (1,595) (187) (26) (489) (446) (2,788)
Reversal (3) (117) (80) (23) (30) (243) (496)
Interest effect 0 107 31 0 0 11 149
Other changes 1 (17) (1) (2) 8 (86) (97)
At December 31, 2016 197 2,554 1,652 328 423 1,234 6,388
Of which: current 178 1,472 51 318 423 626 3,068
Changes in the composition of the Group 0 1 0 0 0 1 2
Currency translation adjustments 0 (59) (65) (2) (25) (44) (195)
Addition 41 1,911 121 86 754 432 3,345
Use (54) (1,520) (57) (69) (423) (390) (2,513)
Reversal (17) (121) (68) (17) (23) (163) (409)
Interest effect 0 0 22 0 0 11 33
Other changes 0 (109) (14) 0 0 (1) (124)
At December 31, 2017 167 2,657 1,591 326 706 1,080 6,527
Of which: current 166 1,481 40 311 706 668 3,372

In the measurement of the other provisions, Deutsche Telekom is exposed to interest rate fluctuations, which is why the effect of a possible change in the interest rate on the principal non-current provisions was simulated. The other, non-staff-related provisions are discounted using maturity-­related discount rates specific for the respective currency area. To this end, Deutsche Telekom determines discount rates with maturities of up to 30 years. In 2017, the discount rates ranged from 0.00 to 3.08 percent (2016: from 0.00 to 3.38 percent) in the euro currency area and from 2.42 to 4.96 percent (2016: from 1.72 to 5.56 percent) in the U.S. dollar ­currency area. If the discount rate were increased by 50 basis points with no other change in the assumptions, the present value of the principal other non-current provisions would decrease by EUR 111.6 million (December 31, 2016: EUR 107.7 million). If the discount rate were decreased by 50 basis points with no other change in the assumptions, the present value of the principal other non-current provisions would increase by EUR 103.1 million (December 31, 2016: EUR 114.1 million).

Provisions for termination benefits and other personnel provisions include provisions for staff restructuring. These provisions developed as follows in the financial year: 

millions of €
  Jan. 1, 2017 Addition Use Reversal Other changes Dec. 31, 2017
Severance and voluntary redundancy models 197 41 (54) (17) 0 167
Partial retirement 420 437 (294) 0 (74) 489
  617 478 (348) (17) (74) 656
Of which: current 311         316

Other provisions for personnel costs include provisions for deferred ­compensation and allowances, as well as for anniversary gifts.

Provisions for restoration obligations include the estimated costs for dismantling and removing an asset, and restoring the site on which it is located. The estimated costs are included in the costs of the relevant asset.

The provisions for litigation risks primarily relate to possible settlements attributable to pending lawsuits. In the Toll Collect arbitration proceedings, appropriate provisions for risks have been recognized in the statement of financial position since 2014. For further information, please refer to the explanations in Note 32 “Contingencies.”

Provisions for sales and procurement support are recognized for dealer commissions, subsidies for advertising expenses, and reimbursements.

Miscellaneous other provisions include a large number of low-value individual items, such as provisions related to executory contracts, the disposal of businesses and site closures, in particular in prior financial years, as well as warranty and environmental damage provisions.