Weighted Average Shares

12 Months Ended

Dec. 31, 2020

Weighted-average shares were calculated as follows (in thousands):


	Year Ended December 31,
	2020	2019	2018
Basic weighted-average common shares outstanding	173,489	171,194	172,333
Effect of dilutive stock awards	3,103	4,075	5,073
Diluted weighted-average common and common-equivalent shares outstanding	176,592	175,269	177,406

Stock options to purchase 4,371,194, 5,735,608, and 2,650,164 shares of common stock, on a weighted-average basis, were outstanding in 2020, 2019, and 2018, respectively, but were not included in the calculation of dilutive net income per share because they were anti-dilutive. Restricted stock units totaling 3,826 and 13,092 shares of common stock, on a weighted-average basis, were outstanding in 2020 and 2019, respectively, but were not included in the calculation of dilutive net income per share because they were anti-dilutive. There were no anti-dilutive restricted stock units outstanding, on a weighted-average basis, in 2018.