(12) Basic and Diluted Earnings per Share

Potential shares of common stock are included in the diluted earnings per share calculation when dilutive. Potential shares of common stock, consisting of common stock issuable upon exercise of outstanding stock options, are calculated using the treasury stock method.

The following table sets forth the computation of basic and diluted earnings per share (in thousands, except per share data) for the periods indicated:

	Years Ended December 31,
	2017		2016		2015
Numerator:
Net income	$	17,643	$	90,908	$	105,931

Denominator:
Weighted average common shares of class A common stock		9,409		9,390		9,320
Weighted average common shares of class B common stock		2,035		2,035		2,035
Total weighted average common stock shares outstanding		11,444		11,425		11,355
Effect of dilutive securities:
Employee stock options		103		91		184
Adjusted weighted average shares		11,547		11,516		11,539

Earnings per share:
Basic earnings per share	$	1.54	$	7.96	$	9.33
Diluted earnings per share	$	1.53	$	7.89	$	9.18

For the years ended December 31, 2017, 2016, and 2015, stock options issued under the 2013 Equity Plan to purchase a weighted average of approximately 398,000, 391,000, and 262,000 shares of class A common stock, respectively, were excluded from the diluted earnings per share calculation because their impact would have been anti-dilutive.