Table:
|  |  | Year Ended June 30, |  |
| --- | --- | --- | --- |
|  | 2019 | 2018 | 2017 |
| Weighted–average fair value of options granted | $8.39 | $7.58 | $7.06 |
| Weighted-average assumptions used: |  |  |  |
| Expected volatility | 25.72% | 26.95% | 28.32% |
| Risk–free interest rate | 2.57% | 2.18% | 1.46% |
| Expected dividend yield | 1.54% | 1.50% | 1.43% |
| Expected life (in years) | 4.44 | 4.38 | 4.51 |
| Forfeiture rate (based on historical rates) | 6% | 6% | 5% |
| Average exercise share price | $38.81 | $34.60 | $31.75 |
| Derived service period (in years)* | N/A | N/A | 1.79 |
Paragraphs:
For the periods indicated, the weighted-average fair value of options and weighted-average assumptions were as follows:
*Options valued using Monte Carlo Valuation Method
As of June 30, 2019, the total compensation cost related to the unvested stock option awards not yet recognized was approximately $24.1 million, which will be recognized over a weighted-average period of approximately 3.0 years.
No cash was used by us to settle equity instruments granted under share-based compensation arrangements in any of the periods presented.
We have not capitalized any share-based compensation costs as part of the cost of an asset in any of the periods presented.
For the year ended June 30, 2019, cash in the amount of $35.6 million was received as the result of the exercise of options granted under share-based payment arrangements. The tax benefit realized by us during the year ended June 30, 2019 from the exercise of options eligible for a tax deduction was $2.9 million.
For the year ended June 30, 2018, cash in the amount of $54.4 million was received as the result of the exercise of options granted under share-based payment arrangements. The tax benefit realized by us during the year ended June 30, 2018 from the exercise of options eligible for a tax deduction was $1.5 million.
For the year ended June 30, 2017, cash in the amount of $20.8 million was received as the result of the exercise of options granted under share-based payment arrangements. The tax benefit realized by us during the year ended June 30, 2017 from the exercise of options eligible for a tax deduction was $2.2 million.
Question:
How was the derived service period calculated?
Answer: using Monte Carlo Valuation Method