Table:
| Year Ended December 31 |  |  |
| --- | --- | --- |
|  | 2019 | 2018 |
| Common stock, vested at issuance and nonvested at issuance | $721 | $555 |
| Stock options | 354 | 132 |
| Restricted stock units | 225 | 103 |
| Compensation expense related to common stock awards issued under equity incentive plan | $          1,300 | $            790 |
Paragraphs:
Equity Incentive Plan
Our board of directors administers the plan, determines vesting schedules on plan awards and may accelerate the vesting schedules for award recipients. The stock options granted under the plan have terms of up to 10 years. As of December 31, 2019, awards for the purchase of 4,236,719 shares have been granted and remain outstanding (common stock options, common stock and restricted stock units) and 2,063,281 shares are reserved for future grants under the 2014 Plan.
Share-based compensation expenses related to stock options, stock and restricted stock units issued to employees and directors are included in selling, general and administrative expenses. The following table provides a detail of share-based compensation expense (in thousands).
Question:
What is the change in the common stock value between 2018 and 2019?
Answer: 721 - 555  = 166