Years Ended December 31,

2011

2010

2009

Basic net income per share:

Net income

$

195,621

$

273,371

$

149,279

Weighted average number of common shares outstanding

47,731,265

49,522,202

51,647,267

Basic net income per share

$

4.10

$

5.52

$

2.89

Diluted net income per share:

Net income

$

195,621

$

273,371

$

149,279

Weighted average number of common shares outstanding

47,731,265

49,522,202

51,647,267

Dilutive effect of stock options and non-vested stock awards

1,593,018

1,085,806

662,001

Dilutive effect of assumed conversion of the 2.0% Convertible Senior Notes

1,525,271

—

Dilutive effect of warrants

313,554

—

Weighted average number of common shares and dilutive potential common shares outstanding

51,163,108

50,608,008

52,309,268

Diluted net income per share

$

3.82

$

5.40

$

2.85