Table:
| Reconciliation of Non-GAAP measure - operating expenses and operating income from continuing operations, excluding certain items (in thousands) | Years Ended December 31, |  |
| --- | --- | --- |
|  | 2019 | 2018 |
| Gross profit from continuing operations, as reported | $ 315,652 | $365,607 |
| Adjustments to gross profit: |  |  |
| Stock-based compensation | 525 | 742 |
| Facility expansion and relocation costs | 3,891 | 1,328 |
| Acquisition-related costs | 8,290 | 569 |
| Non-GAAP gross profit | 328,358 | 368,246 |
| Non-GAAP gross margin | 41.6% | 51.2% |
| Operating expenses from continuing operations, as reported | 261,264 | 194,054 |
| Adjustments: |  |  |
| Amortization of intangible assets | (12,168) | (5,774) |
| Stock-based compensation | (6,803) | (8,961) |
| Acquisition-related costs | (12,002) | (1,726) |
| Facility expansion and relocation costs | (948) | (518) |
| Restructuring charges | (5,038) | (4,239) |
| Non-GAAP operating expenses | 224,305 | 172,836 |
| Non-GAAP operating income | $  104,053 | $  195,410 |
Paragraphs:
Non-GAAP Results
Management uses non-GAAP operating income and non-GAAP EPS to evaluate business performance without the impacts of certain non-cash charges and other charges which are not part of our usual operations. We use these non- GAAP measures to assess performance against business objectives, make business decisions, including developing budgets and forecasting future periods. In addition, management’s incentive plans include these non-GAAP measures as criteria for achievements. These non-GAAP measures are not in accordance with U.S. GAAP and may differ from non- GAAP methods of accounting and reporting used by other companies. However, we believe these non-GAAP measures provide additional information that enables readers to evaluate our business from the perspective of management. The presentation of this additional information should not be considered a substitute for results prepared in accordance with U.S. GAAP.
The non-GAAP results presented below exclude the impact of non-cash related charges, such as stock-based compensation and amortization of intangible assets. In addition, they exclude discontinued operations and other nonrecurring items such as acquisition-related costs and restructuring expenses, as they are not indicative of future performance. The tax effect of our non-GAAP adjustments represents the anticipated annual tax rate applied to each non-GAAP adjustment after consideration of their respective book and tax treatments and effect of adoption of the Tax Act.
Question:
What was the percentage change in acquisition-related costs between 2018 and 2019?