Selling, general and administrative expenses
Selling, general and administrative expenses for the year ended December 31, 2019, increased $67.0 million, or 51%, compared to the year ended December 31, 2018, primarily as a result of the reversal of all stock-based compensation related to the 2017 Performance Award (as defined in Note 8 to the consolidated financial statements included elsewhere in this Annual Report) during the year ended December 31, 2018, as late achievement of the 2017 Performance Award did not occur, and charges related to the default of our partner in China in 2019.
Cost of products sold
Cost of products sold for the year ended December 31, 2019, increased $8.5 million, or 7%, compared to the year ended December 31, 2018, primarily as a result of increased food and merchandise sales driven by the continued growth of our all season dining pass program and operations at our new properties. Cost of products sold as a percentage of non-admissions revenue for the year ended December 31, 2019, increased slightly as compared to the year ended December 31, 2018, primarily due to the significant portion of our revenue growth being driven by our new parks that currently have lower gross margins.
Depreciation and amortization expense
Depreciation and amortization expense for the year ended December 31, 2019, increased $2.5 million, or 2%, compared to the year ended December 31, 2018. The increase in depreciation and amortization expense is primarily the result of new asset additions related to our ongoing capital investments, partially offset by asset retirements.
Loss on disposal of assets
Loss on disposal of assets increased by $0.3 million, or 15%, for the year ended December 31, 2019, compared to the year ended December 31, 2018, primarily as a result of increased asset disposals in conjunction with the execution of our ongoing capital program during the current year relative to the prior year.
Interest expense, net
Interest expense, net increased $6.1 million, or 6%, for the year ended December 31, 2019, compared to the year ended December 31, 2018, primarily as a result of incremental borrowings under the Second Amended and Restated Credit Facility, partially offset by lower interest rates.
Loss on debt extinguishment
In conjunction with the amendments to the Second Amended and Restated Credit Facility entered into in April 2019 and October 2019, we recognized a loss on debt extinguishment of $6.2 million and $0.3 million, respectively. See Note 8 to the consolidated financial statements included elsewhere in this Annual Report for further discussion.
Income tax expense
Income tax expense was $91.9 million for the year ended December 31, 2019, compared to $95.9 million for the year ended December 31, 2018. Income taxes decreased primarily due to lower earnings before taxes for the year ended in December 31, 2019 compared to the year ended December 31, 2018 partially offset by the recognition of a valuation allowance against foreign tax credit carryforwards that we estimate will expire unutilized due to changes in estimated future foreign source income related to the termination of our agreements with our partner in China.
See Note 11 to the consolidated financial statements included elsewhere in this Annual Report for further discussion.