Table:
|  | Years Ended December 31, |  | Change |  |
| --- | --- | --- | --- | --- |
|  | 2019 | 2018 | $ | % |
|  |  | (dollars in thousands) |  |  |
| Research and development | $17,845 | $22,450 | $(4,605) | (21)% |
| Percent of revenues, net | 36% | 38% |  |  |
Paragraphs:
Research and Development
Research and development expenses in 2019 decreased by $4.6 million, or 21%, as compared to 2018. The decrease was primarily due to a reduction in the number of full-time research and development personnel, resulting in a decrease of $3.1 million in compensation expense and $0.6 million in allocated facilities and information technology costs as compared to 2018. We did not incur restructuring costs in 2019, as compared to 2018 when $0.1 million was incurred as part of the 2018 Restructuring Plan (refer to Note 4 of the accompanying consolidated financial statements). Finally, the decrease was further driven by lower professional fees of $0.6 million, as we reduced the number of research and development contractors as compared to 2018.
Question:
What led to the decrease in research and development expenses in 2019?
Answer: reduction in the number of full-time research and development personnel