pre_text: 10.5. Intangible assets Impairment testing of goodwill Goodwill has been allocated to the listed group (NSR). Management have determined that the listed group, which is considered one operating segment (see note 4), is the appropriate CGU against which to allocate these intangible assets owing to the synergies arising from combining the portfolios of the Group. The recoverable amount of the listed group has been determined based on the fair value less costs of disposal method using the fair value quoted on an active market. As at 1 July 2019, NSR had 773,343,956 stapled securities quoted on the Australian Securities Exchange at $1.745 per security providing a market capitalisation of $1,349.5m. This amount is in excess of the carrying amount of the Group’s net assets at 30 June 2019 which includes the contract for future issue of equity recognised as contributed equity within the statement of financial position at this date (see note 13). Had the security price decreased by 2.5% the market capitalisation would still have been in excess of the carrying amount.
table: 2019 2018
table: Notes $'000 $'000
table: Goodwill
table: Opening and closing net book value 43,954 43,954
table: Other intangible assets
table: Opening net book value 2,051 1,582
table: Additions 1,079 864
table: Amortisation 6 (584) (395)
table: Closing net book value 2,546 2,051
table: Total intangible assets 46,500 46,005
question: Analyse this data from a financial earnings document. What is the change in Other intangible assets Opening net book value from 2018 to 2019?