4. Per Share Data

We determine basic earnings per share based on the weighted average number of shares of common stock outstanding during the period and we consider any participating securities for purposes of applying the two-class method. We determine diluted earnings per sharef425,508 based on the weighted average number of shares of common stock outstanding combined with the incremental weighted average shares that would have been outstanding assuming all potentially dilutive securities were converted into common shares at the earliest date possible. The following table sets forth the computation of our basic and diluted earnings per share.

	For the Three Months Ended March 31,
	2015		2014
Net Income attributable to Common Stockholders — Basic and Diluted	$	539,134	$	341,648


Weighted Average Shares Outstanding — Basic and Diluted		311,101,297		310,622,570

For the three months ended March 31, 2015, potentially dilutive securities include units that are exchangeable for common stock and long-term incentive performance, or LTIP, units granted under our long-term incentive performance programs that are convertible into units and exchangeable for common stock. No securities had a dilutive effect for the three months ended March 31, 2015 and 2014. We accrue dividends when they are declared.