| Share grants and Fair Value |
| | Shares | | | Fair Value at Date of Grant ($Millions) | | | | | | | In connection with IPO | 927,943 | | $ | 27.8 | July 31, 2007 | 16,665 | | | 0.4 | December 31, 2007 | 1,055,206 | | | 32.9 | December 31, 2008 | 2,065,432 | | | 35.6 | December 31, 2009 | 2,448,031 | | | 42.8 | December 31, 2010 | 2,513,738 | | | 43.2 | December 31, 2011 | 3,411,613 | | | 50.8 | January 6, 2012 | 1,215,866 | | | 18.4 | December 31, 2012 | 3,629,960 | | | 50.5 | | | 17,284,454 | | $ | 302.4 |
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| 2007 Stock Incentive Plan, ROI Summary |
| | Shares | | | | 2007 Stock | | | 2007 ROI Unit | | | | Incentive Plan | | | Stock Plan | | | | Shares | | | Shares | | Balance, December 31, 2012 | 12,402,482 | | | 169,289 | | | | | | | | | Granted | - | | | - | | Forfeited | (50,827 | ) | | (6,423 | ) | Distributed | (3,605 | ) | | (1,742 | ) | Balance, March 31, 2013 | 12,348,050 | | | 161,124 | |
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