Table:
|  |  | For the Year Ended December 31, |  |
| --- | --- | --- | --- |
|  | 2019 | 2018 | 2017 |
| Stock-based compensation cost: |  |  |  |
| Common stock warrants | $— | $512 | $484 |
| Stock options | 16,489 | 13,279 | 11,295 |
| Restricted stock units | 14,585 | 90 | — |
| Employee stock purchase plan | 3,326 | 2,069 | — |
| Total stock-based compensation cost | $34,400 | $15,950 | $11,779 |
Paragraphs:
Stock-Based Compensation
The Company recognized total stock-based compensation cost related to equity incentive awards as follows (in thousands):
A small portion of stock-based compensation cost above is capitalized in accordance with the accounting guidance for internal-use software. The Company uses the straight-line attribution method for recognizing stock-based compensation expense.
Question:
What is the change in common stock warrants between 2017 and 2018?
Answer: 512 - 484  = 28