— 111) (15) Balance as of December 31 2 452 231 1 101 2,815 2,765 Cumulative amortization Balance as of January I 317 — — 9 326 117 Amoruzaton of the period rotes 76 and 77(a) 200 — — 9 209 209 Balance as of December 31 517 — — 18 535 326 Net book value 1.965 231 1 53 228