Basic earnings per share (“EPS”) amounts are calculated by dividing earnings available to common shareholders by the weighted average number of common shares outstanding. Diluted EPS amounts assume the issuance of common stock for all potentially dilutive common shares outstanding. The following table shows the basic and diluted earnings per share for three and six months ended June 30, 2011 and 2010:

	For the three months ended June 30,
	2011							2010
	Income			Shares (000)		Per-Share		Income			Shares (000)		Per-Share
Net income	$	23,986						$	5,146
Amount allocated to common shareholders		91.97	%						91.79	%
Basic EPS:
Income allocable to common shareholders		22,061			93,105	$	0.24		4,723			92,672	$	0.05
Effect of Dilutive Securities: Plus:
Options		—			119				—			40
Service-based stock awards		—			343				—			620
Diluted EPS:
Income applicable to common shareholders with assumed conversion	$	22,061			93,567	$	0.24	$	4,723			93,332	$	0.05

	For the six months ended June 30,
	2011							2010
	Income			Shares (000)		Per-Share		Income			Shares (000)		Per-Share
Net income	$	49,032						$	11,478
Amount allocated to common shareholders		91.91	%						91.76	%
Basic EPS:
Income allocable to common shareholders		45,066			93,036	$	0.48		10,532			92,611	$	0.11
Effect of Dilutive Securities: Plus:
Options		—			116				—			46
Service-based stock awards		—			280				—			561
Diluted EPS:
Income applicable to common shareholders with assumed conversion	$	45,066			93,432	$	0.48	$	10,532			93,218	$	0.11

Our Series A Convertible Preferred Stock has similar characteristics of a “participating security” as described by ASC 260-10-45 “Participating Securities and the Two-Class Method”. In accordance with the guidance in the ASC 260-10-45, we calculate basic EPS using the Two-Class Method, allocating undistributed income to our preferred shareholder consistent with its participation rights, and diluted EPS using the If-Converted Method, when applicable.

The generally accepted accounting principles for reporting EPS do not require the presentation of basic and diluted EPS for securities other than common stock and the EPS amounts, as presented, only pertain to our common stock.

The Two-Class Method is an earnings allocation formula that determines earnings per share for common shares and participating securities according to dividends declared (or accumulated) and the participation rights in undistributed earnings.

The holders of our convertible preferred stock do not have a contractual obligation to share in the losses of Century. Thus, in periods where we report net losses, we will not allocate the net losses to the convertible preferred stock for the computation of basic or diluted EPS.

Options to purchase 641,187 and 690,075 shares of common stock were outstanding as of June 30, 2011 and June 30, 2010, respectively. For the three and six months ended June 30, 2011, approximately 349,000 options were excluded from the calculation of EPS because their exercise price exceeded the average market price of the underlying common stock. Shares to be issued upon the assumed conversion of our convertible debt were excluded from the calculation of diluted EPS because our 1.75% convertible senior notes were redeemed in May 2011.

For the three and six months ended June 30, 2010, approximately 381,000 options were excluded from the calculation of EPS because their exercise price exceeded the average market price of the underlying common stock. Shares to be issued upon the assumed conversion of our convertible debt were excluded from the calculation of diluted EPS because the average price for our common stock in the three and six months ended June 30, 2010 was below the conversion price of our 1.75% convertible senior notes.

Service-based stock for which vesting is based upon continued service is not considered issued and outstanding shares of common stock until vested and issued. However, the service-based stock is considered a common stock equivalent and, therefore, the weighted average service-based stock is included, using the treasury stock method, in common shares outstanding for diluted earnings per share computations if they have a dilutive effect on earnings per share. The weighted average service-based stock outstanding at June 30, 2011 and June 30, 2010 was approximately 343,000 and 529,000 shares, respectively.

For the calculation of basic and diluted EPS for the three and six months ended June 30, 2011 and June 30, 2010, using the Two-Class Method, we allocated our undistributed income to the convertible preferred stock as shown in the following tables:

	Three months ended June 30, 2011				Three months ended June 30, 2010
	Weighted average shares outstanding		Undistributed earnings		Weighted average shares outstanding		Undistributed earnings
Common stock (in thousands)		93,105	$	22,061		92,672	$	4,723
Preferred stock (in thousands) (1)		8,125		1,925		8,294		423
Total		101,230	$	23,986		100,966	$	5,146

	Six months ended June 30, 2011				Six months ended June 30, 2010
	Weighted average shares outstanding		Undistributed earnings		Weighted average shares outstanding		Undistributed earnings
Common stock (in thousands)		93,036	$	45,066		92,611	$	10,532
Preferred stock (in thousands) (1)		8,187		3,966		8,319		946
Total		101,223	$	49,032		100,930	$	11,478

(1)	Represents the weighted-average participation rights of our preferred shareholder as if it held the number of common shares into which its shares of preferred stock are convertible as of the record date.