Table:
| Year ended December 31, |  |  |  |
| --- | --- | --- | --- |
| (EUR million) | 2018 | 2019 | % Change |
| Front-end: |  |  |  |
| Research and development expenses | 125.3 | 150.7 | 20% |
| Capitalization of development expenses | (49.7) | (60.2) | 21% |
| Research and development grants and credits | (0.3) | – | – |
| Amortization of capitalized development  expenses | 12.0 | 15.6 | 30% |
|  | 87.3 | 106.1 | 22% |
| Impairment capitalized development expenses | 1.3 | 4.8 | – |
| Total | 88.6 | 110.8 | 25% |
Paragraphs:
RESEARCH AND DEVELOPMENT EXPENSES
Total research and development (R&D) expenses, excluding impairment charges, increased by 22% in 2019 compared to the previous year, mainly as a result of higher development activities. As a percentage of sales (excluding the patent litigation & arbitration settlement), R&D expenses decreased to 10% compared to 11% in 2018. Currency changes resulted in a 4% increase in R&D expenses year-over-year.
Total research and development expenses developed as follows:
Impairment of capitalized development expenses related primarily to the development of new technology that is now no longer in-demand from customers.
We continue to invest strongly in R&D. As part of our R&D activities, we are engaged in various development programs with customers and research institutes. These allow us to develop products that meet customer requirements and obtain access to new technology and expertise. The costs relating to prototypes and experimental models, which we may subsequently sell to customers, are charged to the cost of sales.
Our R&D operations in the Netherlands, Belgium, and the United States receive research and development grants and credits from various sources.
Question:
What are the years included in the table for Total research and development expenses?
Answer: 2018, 2019