Income per Share

6 Months Ended

Jun. 30, 2011

Note 8. Income per Share

Basic income per share is based on the weighted average number of common shares outstanding during the period. Diluted income per share includes additional common shares that would have been outstanding if potential common shares with a dilutive effect had been issued.

A reconciliation of the number of shares used for the basic and diluted income per share calculations is as follows:

	Three Months Ended				Six Months Ended
	June 30				June 30
Millions of shares	2011		2010		2011		2010
Basic weighted average common shares outstanding		916		906		915		906
Dilutive effect of stock options		5		3		5		2
Diluted weighted average common shares outstanding		921		909		920		908

Excluded from the computation of diluted income per share are options to purchase two million and one million shares of common stock that were outstanding during the three and six months ended June 30, 2011 and six million shares that were outstanding during both the three and six months ended June 30, 2010. These options were outstanding during these periods but were excluded because they were antidilutive, as the option exercise price was greater than the average market price of the common shares.