Weighted Average Shares Outstanding

Net income per common share is computed in accordance with accounting standards related to earnings per share. Basic earnings per share is calculated using the weighted-average number of common shares outstanding during the year. Share-based payment awards that entitle their holders to receive nonforfeitable dividends before vesting should be considered participating securities and, as such, should be included in the calculation of basic earnings per share. The Company’s restricted stock unit awards which contain nonforfeitable rights to dividends are considered participating securities. Diluted earnings per share reflects the assumed exercise and conversion of all dilutive securities. Shares held by the Retirement Savings Plan are considered outstanding for both basic and diluted earnings per share. There are no significant adjustments to net income for purposes of computing income available to common stockholders for the years ended December 31, 2017, 2016 and 2015. A reconciliation of the weighted-average number of common shares outstanding used in the calculation of basic and diluted earnings per share follows:



	Weighted-Average Common Shares Outstanding
	2017	2016	2015
Basic	54,073,407	54,191,013	55,028,063
Dilutive effect of:
Stock options	258,052	166,986	206,778
Performance share awards	273,839	273,314	278,378
Diluted	54,605,298	54,631,313	55,513,219

The calculation of weighted-average diluted shares outstanding excludes all anti-dilutive shares. During 2017, 2016 and 2015, the Company excluded 46,450, 262,336 and 214,032 stock awards, respectively, from the calculation of diluted weighted-average shares outstanding as the stock awards were considered anti-dilutive.