Notes to Consolidated Financial Statements [in thousands of Canadian dollars, except per share amounts] December 31, 2012 and 2011 During the year, CI granted 2,232,412 options [2011 - 1,577,170 options] to employees. The fair value method of accounting is  used for the valuation of the 2012 and 2011 share option grants. Compensation expense is recognized over the three-year  vesting period, assuming an estimated forfeiture rate of 0% to 1.4%, [options issued 2011 – 0% to 1%], with an offset to  contributed surplus. When exercised, amounts originally recorded against contributed surplus as well as any consideration  paid by the option holder is credited to share capital. The fair value of the 2012 and 2011 option grants was estimated using  the Black-Scholes option-pricing model with the following weighted-average assumptions: (*) Based on the historical volatility of CI’s share price  The maximum number of shares that may be issued under the Share Option Plan is 14,000,000 shares. As at December 31,  2012, there are 6,363,963 shares [2011 - 6,018,092 shares] reserved for issuance on exercise of share options. These options  vest over periods of up to five years, may be exercised at prices ranging from $11.60 to $22.45 per share and expire at dates  up to 2017. 69 Year of grant  2012  2012  2011  2011 # of options grants  [in thousands] 243 1,989 370 1,207 Dividend yield  4.892% – 5.257%  4.837% – 5.197%  4.514% – 4.833%  4.702% – 5.035% Expected volatility (*)  18%  18%  20%  20% Risk-free interest rate  1.335% – 1.439%  1.374% – 1.528%  2.276% – 2.637%  2.202% – 2.592% Expected life  [years] 2.7 – 4.0  2.7 – 4.0  3.0 – 4.2  3.0 – 4.2 Forfeiture rate  0%  1.4%  0%  1% Fair value per stock option  $1.81 – $2.01  $1.84 – $2.06  $2.40 – $2.71  $2.26 – $2.54 Exercise price  $21.73  $21.98  $22.45  $21.55