December 31,
2019
2018
Owned assets:
Network equipment
$566,936
$538,761
Leasehold improvements
227,388
214,495
System infrastructure
134,726
124,018
Software
10,035
9,963
Office and other equipment
18,169
16,711
Building
1,252
1,277
Land
106
108
958,612
905,333
Less—Accumulated depreciation and amortization
(790,033)
(736,356)
168,579
168,977
Assets under finance leases:
IRUs
408,170
395,170
Less—Accumulated depreciation and amortization
(207,820)
(188,822)
200,350
206,348
Property and equipment, net
$368,929
$375,325

text: 2. Property and equipment:
text: Property and equipment consisted of the following (in thousands):
text: Depreciation and amortization expense related to property and equipment and finance leases was $80.2 million, $81.2 million and $75.9 million, for 2019, 2018 and 2017, respectively.
text: The Company capitalizes the compensation cost of employees directly involved with its construction activities. In 2019, 2018 and 2017, the Company capitalized compensation costs of $10.7 million, $10.5 million and $9.7 million respectively. These amounts are included in system infrastructure costs.
text: Exchange agreement
text: In 2019, 2018 and 2017 the Company exchanged certain used network equipment and cash consideration for new network equipment. The fair value of the new network equipment received was estimated to be $3.3 million, $3.2 million and $9.1 million resulting in gains of $1.0 million, $1.0 million and $3.9 million respectively. The estimated fair value of the equipment received was based upon the cash consideration price the Company pays for the new network equipment on a standalone basis (Level 3).
text: Installment payment agreement
text: The Company has entered into an installment payment agreement (“IPA”) with a vendor. Under the IPA the Company may purchase network equipment in exchange for interest free note obligations each with a twenty-four month term. There are no payments under each note obligation for the first six months followed by eighteen equal installment payments for the remaining eighteen month term. As of December 31, 2019 and December 31, 2018, there was $12.5 million and $11.2 million, respectively, of note obligations outstanding under the IPA, secured by the related equipment. The Company recorded the assets purchased and the present value of the note obligation utilizing an imputed interest rate. The resulting discounts totaling $0.4 million and $0.4 million as of December 31, 2019 and December 31, 2018, respectively, under the note obligations are being amortized over the note term using the effective interest rate method.

Questions:
question: What are the respective values of network equipment in 2018 and 2019?
answer: $538,761
$566,936
scale: thousand
question: What are the respective values of leasehold improvements in 2018 and 2019?
answer: 214,495
227,388
scale: thousand
question: What are the respective values of system infrastructure in 2018 and 2019?
answer: 124,018
134,726
scale: thousand
question: What is the percentage change in the value of network equipment between 2018 and 2019?
answer: 5.23
derivation: (566,936 - 538,761)/538,761 
scale: percent
question: What is the percentage change in the value of leasehold improvements between 2018 and 2019?
answer: 6.01
derivation: (227,388 - 214,495)/214,495 
scale: percent
question: What is the percentage change in the value of system infrastructure between 2018 and 2019?
answer: 8.63
derivation: (134,726 - 124,018 )/124,018  
scale: percent