9. Income per Unit

The following is a summary of basic and diluted income per unit (in thousands, except unit and per unit amounts):



	Three Months Ended June 30,		Six Months Ended June 30,
	2014	2013	2014	2013

Net income available to common unitholders	$ 42,383	$ 48,013	$ 77,262	$ 91,494

Weighted average units outstanding—basic	136,615,338	130,973,952	133,894,119	129,936,759
Potentially dilutive common units:
Stock options	45,278	68,146	43,023	69,304
Unvested incentive units	74,345	135,185	65,847	120,222
2014 market performance-based awards	55,640	-	27,820	-
Weighted average units outstanding—diluted	136,790,601	131,177,283	134,030,809	130,126,285

Income per unit:
Basic	$ 0.31	$ 0.37	$ 0.58	$ 0.70
Diluted	$ 0.31	$ 0.37	$ 0.58	$ 0.70

We have excluded the following potentially dilutive securities in the calculations above as they would be antidilutive or not dilutive:


	Three Months Ended June 30,		Six Months Ended June 30,
	2014	2013	2014	2013

Potentially dilutive 2029 Debentures	1,121,910	6,609,993	3,948,379	6,600,286
Potentially dilutive Series D Cumulative Convertible Preferred Units	-	-	-	949,299
Potentially dilutive Series E Cumulative Redeemable Preferred Units	5,060,744	4,929,167	5,367,507	4,655,435
Potentially dilutive Series F Cumulative Redeemable Preferred Units	3,209,512	3,126,066	3,404,060	2,952,466
Potentially dilutive Series G Cumulative Redeemable Preferred Units	4,388,483	3,893,598	4,654,496	1,957,555
Potentially dilutive Series H Cumulative Redeemable Preferred Units	6,437,332	-	3,449,841	-
	20,217,981	18,558,824	20,824,283	17,115,041