Table:
|  | 2019 | 2018 |
| --- | --- | --- |
|  | F19 LTI | F18 LTI |
| Grant date (1) | 30 Nov 2018 | 31 Oct 2017 |
| Performance period start date | 1 Jul 2018 | 1 Jul 2017 |
| Exercise date | 1 Jul 2021 | 1 Jul 2020 |
| Expected volatility (2) | 15.0% | 16.0% |
| Expected dividend yield | 4.0% | 4.0% |
| Risk-free interest rate | 2.1% | 1.9% |
| Weighted average fair value at grant date | $24.63 | $20.23 |
Paragraphs:
Share-based payments expense for the period was $62,028,117 (2018: $57,710,434).
The variables in the table below are used as inputs into the model to determine the fair value of performance rights.
(1) Grant date represents the offer acceptance date.
(2) The expected volatility is based on the historical implied volatility calculated based on the weighted average remaining life of the performance rights adjusted for any expected changes to future volatility due to publicly available information.
Question:
What is the change in expected volatility between 2018 and 2019?
Answer: 16.0% - 15.0%  = 1