pre_text: Property, plant and equipment, net Property, plant and equipment, net consisted of the following at December 31, 2019 and 2018 (in thousands): We periodically assess the estimated useful lives of our property, plant and equipment whenever applicable facts and circumstances indicate a change in the estimated useful life of an asset may have occurred. During the year ended December 31, 2019, we revised the estimated useful lives of certain core Series 6 manufacturing equipment from 10 years to 15 years. Such revision was primarily due to the validation of certain aspects of our Series 6 module technology, including the nature of the manufacturing process, the operating and maintenance cost profile of the manufacturing equipment, and the technology’s compatibility with our long-term module technology roadmap. We expect the revised useful lives to reduce depreciation by approximately $15.0 million per year. Depreciation of property, plant and equipment was $176.4 million, $109.1 million, and $91.4 million for the years ended December 31, 2019, 2018, and 2017, respectively.
table: 2019 2018
table: Land $14,241 $14,382
table: Buildings and improvements . 664,266 567,605
table: Machinery and equipment . 2,436,997 1,826,434
table: Office equipment and furniture . 159,848 178,011
table: Leasehold improvements 48,772 49,055
table: Construction in progress 243,107 405,581
table: Property, plant and equipment, gross 3,567,231 3,041,068
table: Accumulated depreciation . (1,386,082) (1,284,857)
table: Property, plant and equipment, net $2,181,149 $1,756,211
question: Analyse this data from a financial earnings document. What is the difference between land from 2018 to 2019?