10. Earnings Per Share

Basic net income per share is calculated by dividing the net income attributable to common shares by the weighted-average number of common shares outstanding during the period. Diluted net income per share adjusts basic net income per share for the effects of potentially dilutive common shares, if the effect is not antidilutive. Potentially dilutive common stock consists of shares issuable under the 2010 Plan. The following is a summary of basic and diluted net income per share (in thousands, except share and per share amounts):


	Three Months Ended September 30,				Nine Months Ended September 30,
	2017		2016		2017		2016
Net income attributable to common shares	$	15,758	$	12,180	$	47,693	$	35,476
Weighted-average common shares outstanding - basic		33,878,881		33,425,762		33,758,971		31,906,000
Effect of potentially dilutive common shares:
Stock options		59,201		192,272		98,660		197,166
Unvested awards		176,087		294,121		176,211		258,201
Weighted-average common shares outstanding - diluted		34,114,169		33,912,155		34,033,842		32,361,367
Net income per share attributable to common shares
Basic	$	0.47	$	0.36	$	1.41	$	1.11
Diluted	$	0.46	$	0.36	$	1.40	$	1.10

In the calculations above, we have excluded weighted-average potentially dilutive securities of 1,205 and 7,757 for the three months ended September 30, 2017, and 2016, respectively, and 109,953 and 113,920 for the nine months ended September 30, 2017, and 2016, respectively, as their effect would have been antidilutive.