Table:
| For the year ended | 2019 | 2018 | 2017 |
| --- | --- | --- | --- |
| Stock-based compensation expense by caption |  |  |  |
| Cost of goods sold | $102 | $83 | $88 |
| Selling, general, and administrative | 73 | 61 | 75 |
| Research and development | 68 | 54 | 52 |
|  | $243 | $198 | $215 |
| Stock-based compensation expense by type of award |  |  |  |
| Restricted stock awards | $178 | $140 | $144 |
| Stock options | 33 | 55 | 71 |
| ESPP | 32 | 3 | — |
|  | $243 | $198 | $215 |
Paragraphs:
Stock-based Compensation Expense
The income tax benefit related to share-based compensation was $66 million, $158 million and $97 million for 2019, 2018 and 2017, respectively. The income tax benefits related to share-based compensation for the periods presented prior to the second quarter of 2018 were offset by an increase in the U.S. valuation allowance. Stock-based compensation expense of $30 million and $19 million was capitalized and remained in inventory as of August 29, 2019 and August 30, 2018, respectively. As of August 29, 2019, $439 million of total unrecognized compensation costs for unvested awards, before the effect of any future forfeitures, was expected to be recognized through the fourth quarter of 2023, resulting in a weighted-average period of 1.3 years.
Question:
What is the difference between stock-based compensation expenses between 2018 and 2019?
Answer: $243-$198  = 45