5. 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 share 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 Year Ended December 31,
	2015		2014		2013
Net Income attributable to Common Stockholders — Basic and Diluted	$	1,824,383	$	1,405,251	$	1,316,304


Weighted Average Shares Outstanding — Basic		310,102,746		310,731,032		310,255,168
Effect of stock options		—		—		50

Weighted Average Shares Outstanding — Diluted		310,102,746		310,731,032		310,255,218

For the year ended December 31, 2015 and 2014, 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 material dilutive effect for the years ended December 31, 2015 and 2014. The only securities that had a dilutive effect for the year ended December 31, 2013 were stock options.

We accrue dividends when they are declared. The taxable nature of the dividends declared for each of the years ended as indicated is summarized as follows:

	For the Year Ended December 31,
	2015	2014	2013
Total dividends paid per common share	$6.05	$5.15	$4.65


Percent taxable as ordinary income	94.30%	100.0%	97.50%
Percent taxable as long-term capital gains	5.70%	0.00%	2.50%

	100.0%	100.0%	100.0%

In January 2016, our Board of Directors declared a quarterly cash dividend of $1.60 per share of common stock payable on February 29, 2016 to stockholders of record on February 12, 2016.