The following table shows the different types of expenses allocated to research and development costs for the years ended December 31:
| 2015 | 2016 | 2017 | ||||||||||
| Third-party services | 15,386 | 20,170 | 12,299 | |||||||||
| Personnel expenses | 3,637 | 6,648 | 5,639 | |||||||||
| Legal, consulting and patent expenses | 902 | 758 | 890 | |||||||||
| Cost of Materials | 902 | 1,028 | 994 | |||||||||
| Amortization and depreciation | 308 | 322 | 309 | |||||||||
| Operating lease expenses | 267 | 297 | 345 | |||||||||
| Other expenses | 606 | 957 | 1,013 | |||||||||
| 22,008 | 30,180 | 21,489 | ||||||||||