3. EARNINGS PER SHARE, SHARE REPURCHASES AND DIVIDENDS ON COMMON STOCK

Basic Earnings Per Share

We calculate basic earnings per share by dividing net earnings by the weighted-average number of shares of common stock outstanding during each period.

Diluted Earnings Per Share

Diluted earnings per share include the dilutive effect of awards granted to employees under stock-based compensation plans. The dilutive effect of these securities totaled 1.2 million, 1.6 million and 2.2 million shares for the years ended December 31, 2017, 2016 and 2015, respectively.

Share Repurchases

On May 15, 2013, the company’s board of directors authorized a share repurchase program of up to $4.0 billion of the company’s common stock (the “2013 Repurchase Program”). Repurchases under the 2013 Repurchase Program commenced in September 2013 and were completed in March 2015. On December 4, 2014, the company’s board of directors authorized a new share repurchase program of up to $3.0 billion of the company’s common stock (the “2014 Repurchase Program”). Repurchases under the 2014 Repurchase Program commenced in March 2015 and were completed in March 2016.

On September 16, 2015, the company’s board of directors authorized a new share repurchase program of up to $4.0 billion of the company’s common stock (the “2015 Repurchase Program”). Repurchases under the 2015 Repurchase Program commenced in March 2016 upon the completion of the company’s 2014 Repurchase Program. As of December 31, 2017, repurchases under the 2015 Repurchase Program totaled $1.7 billion; $2.3 billion remained under this share repurchase authorization. By its terms, the 2015 Repurchase Program is set to expire when we have used all authorized funds for repurchases.

Share repurchases take place from time to time, subject to market conditions and management’s discretion, in the open market or in privately negotiated transactions. The company retires its common stock upon repurchase and, in the periods presented, has not made any purchases of common stock other than in connection with these publicly announced repurchase programs.

The table below summarizes the company’s share repurchases to date under the authorizations described above:



Repurchase Program Authorization Date	Amount Authorized (in millions)		Total Shares Retired (in millions)	Average Price Per Share⁽¹⁾		Date Completed	Shares Repurchased (in millions)
							Shares Repurchased (in millions)
							Year Ended December 31
							2017	2016	2015
May 15, 2013	$	4,000	32.8	$	121.97	March 2015	—	—	2.7
December 4, 2014	$	3,000	18.0	$	166.70	March 2016	—	1.4	16.6
September 16, 2015	$	4,000	7.4	$	222.93		1.6	5.9	—
							1.6	7.3	19.3


⁽¹⁾	Includes commissions paid.

Dividends on Common Stock

In May 2017, the company increased the quarterly common stock dividend 11 percent to $1.00 per share from the previous amount of $0.90 per share.

In May 2016, the company increased the quarterly common stock dividend 13 percent to $0.90 per share from the previous amount of $0.80 per share.

In May 2015, the company increased the quarterly common stock dividend 14 percent to $0.80 per share from the previous amount of $0.70 per share.