11. Share-Based Compensation

We are currently issuing options under the 2009 Long-Term Incentive Plan (the “Plan”). We previously issued options under the 1999 Long-Term Incentive Plan, which was replaced with the Plan. The purpose of the Plan is to advance our interests and those of our shareholders by providing incentives to certain persons who contribute significantly to our strategic and long-term performance objectives and growth. An aggregate of not more than 3 million of our Class A common shares, subject to certain adjustments, may be issued under the Plan, and the Plan terminates no later than April 23, 2019. The exercise price for our options is generally equal to the closing market price of our stock at the date of the grant, and the options normally vest at 2% per month for the 50 months beginning in the eleventh month after the grant date. Follow on option grants begin vesting in the first month after grant. We recognize the compensation expense related to share-based payment awards on a straight-line basis over the requisite service periods of the awards, which are generally five years for employees, and two years for board members. Commencing with options granted during 2012, we extended the exercise period from seven to ten years.

The determination of the estimated fair value of share-based payment awards on the date of grant using the Black-Scholes option-pricing model is affected by our stock price as well as assumptions regarding a number of complex and subjective variables. We derive the expected terms from the historical behavior of participant groupings. We base expected volatilities on the historically realized volatility of our stock over the expected term. Our use of historically realized volatilities is based upon the expectation that future volatility over the expected term is not likely to differ significantly from historical results. We base the risk-free interest rate used in the option valuation model on U.S. Treasury zero-coupon issues with remaining terms similar to the expected term on the options. We estimate forfeitures at the time of grant and revise those estimates in subsequent periods if actual forfeitures differ from those estimates. We primarily use historical data by participant groupings to estimate option forfeitures and record share-based compensation expense only for those awards that are expected to vest.

The following are the variables we used in the Black-Scholes option pricing model to determine the estimated grant date fair value for options granted under the Plan for each of the years presented:

The table below presents a summary of option activity under both our plans as of December 31, 2014, and changes during the year then ended:

During 2014, 2013 and 2012, we extended the exercise period on the options of certain former board members and key employees and recognized an additional immediate expense of $0.1 million, $0.1 million and $0.1 million, respectively. On October 11, 2013, we issued 15,759 shares of our Class A common stock under restricted stock award agreements to certain former board members. The estimated fair value of these restricted stock awards was $0.1 million and was based on the closing market price of our stock on October 11, 2013. These restricted stock awards vested 100% on April 10, 2014.

We issue new shares upon the exercise of options. We received $1.8 million and $0.8 million in cash from stock options exercised during 2014 and 2013, respectively. No options were exercised during 2012. The weighted-average grant-date fair value of options granted during the years 2014, 2013, and 2012 was $ 2.98, $3.14, and $2.39, respectively. The total intrinsic value of options exercised during 2014 and 2013 was $0.9 million and $0.1 million, respectively. The total fair value of shares vested was $0.6 million, $0.6 million, and $0.8 million during 2014, 2013, and 2012.

Our share-based compensation cost charged against income was $0.8 million, $0.8 million, and $1.0 million during 2014, 2013, and 2012, respectively, and is included in corporate, general and administration expenses. The total income tax benefit recognized for share-based compensation was $0.3 million, $0.3 million, and $0.4 million for 2014, 2013, and 2012, respectively. As of December 31, 2014, there was $1.6 million of unrecognized cost related to nonvested shared-based compensation arrangements granted under our 2009 and 1999 Long-Term Incentive Plans. We expect that cost to be recognized over a weighted-average period of 3.57 years.