Table:
|  |  | Year Ended |  |
| --- | --- | --- | --- |
|  | April 26, 2019 | April 27, 2018 | April 28, 2017 |
| Cost of product revenues | $ 4 | $ 3 | $ 4 |
| Cost of hardware maintenance and other services revenues | 10 | 10 | 13 |
| Sales and marketing | 67 | 68 | 84 |
| Research and development | 48 | 49 | 59 |
| General and administrative | 29 | 31 | 35 |
| Total stock-based compensation expense | $ 158 | $ 161 | $ 195 |
| Income tax benefit for stock-based compensation | $ 15 | $ 29 | $ 41 |
Paragraphs:
Stock-Based Compensation Expense
Stock-based compensation expense is included in the consolidated statements of operations as follows (in millions):
As of April 26, 2019, total unrecognized compensation expense related to our equity awards was $285 million, which is expected to be recognized on a straight-line basis over a weighted-average remaining service period of 2.1 years.
Question:
Which years does the table provide information for the company's stock-based compensation expense?
Answer: 2019, 2018, 2017