2017 | 2016 | 2015 | |
Risk-free interest rate | 1.18% | 0.82% | 0.63% |
Expected hold period to exercise | 3.0 years | 3.0 years | 3.0 years |
Volatility in the price of the Company's shares | 90.73% | 94.84% | 90% |
Rate of forfeiture | 3.67% | 3.67% | 3.67% |
Dividend yield | Nil | Nil | Nil |
Weighted average fair value of options | $0.28 | $0.17 | $0.24 |