pre_text: 3. Property, Plant and Equipment Assets held under capital leases and included in property, plant and equipment as of September 28, 2019 and September 29, 2018 consisted of the following (in thousands): Amortization of assets held under capital leases totaled $3.8 million, $3.4 million and $3.0 million for fiscal 2019, 2018 and 2017, respectively. Capital lease additions totaled $6.7 million, $11.8 million, and $20.5 million for fiscal 2019, 2018 and 2017, respectively. As of September 28, 2019, September 29, 2018 and September 30, 2017, accounts payable included approximately $10.0 million, $11.2 million and $10.8 million, respectively, related to the purchase of property, plant and equipment, which have been treated as non-cash transactions for purposes of the Consolidated Statements of Cash Flows.
table: 2019 2018
table: Buildings and improvements $23,717 $23,717
table: Machinery and equipment  12,293 10,995
table: Capital assets in progress 11,831 7,747
table: Total property, plant and equipment held under capital leases, gross 47,841 42,459
table: Less: accumulated amortization  (8,762) (6,123)
table: Total property, plant and equipment held under capital leases, net 39,079 36,336
question: Analyse this data from a financial earnings document. What was the change in the gross Total property, plant and equipment held under capital leases between 2018 and 2019?