Table:
|  |  | Year Ended |  | Change |  |  |  |
| --- | --- | --- | --- | --- | --- | --- | --- |
| (Dollars in thousands) | 2019 | 2018 | 2017 | 2019 over 2018 |  | 2018 over 2017 |  |
| Selling, general and administrative | $205,471 | $176,857 | $202,699 | $28,614 | 16% | $(25,842) | (13)% |
| % of net sales . | 6.7% | 7.9% | 6.9% |  |  |  |  |
Paragraphs:
Selling, general and administrative
Selling, general and administrative expense consists primarily of salaries and other personnel-related costs, professional fees, insurance costs, and other business development and selling expenses.
The following table shows selling, general and administrative expense for the years ended December 31, 2019, 2018, and 2017:
Selling, general and administrative expense in 2019 increased compared to 2018 primarily due to higher employee compensation expense, lower accretion expense in 2018 associated with the reduction in our module collection and recycling liability described above, and higher professional fees.
Question:
What are the reasons for higher selling, general and administrative expense in 2019 as compared to 2018?
Answer: Selling, general and administrative expense in 2019 increased compared to 2018 primarily due to higher employee compensation expense, lower accretion expense in 2018 associated with the reduction in our module collection and recycling liability described above, and higher professional fees.