The following is a reconciliation of basic net earnings per share to diluted net earnings per share for the fiscal years ended January 3, 2021, December 29, 2019 and December 30, 2018:


(In Millions Except Per Share Amounts)	2020		2019	2018
Basic net earnings per share	$	5.59	5.72	5.70
Average shares outstanding — basic	2,632.8		2,645.1	2,681.5
Potential shares exercisable under stock option plans	118.3		136.3	139.0
Less: shares repurchased under treasury stock method	(80.4)		(97.8)	(92.5)
Convertible debt shares	—		0.7	0.7
Adjusted average shares outstanding — diluted	2,670.7		2,684.3	2,728.7
Diluted net earnings per share	$	5.51	5.63	5.61

The diluted net earnings per share calculation for fiscal year 2020 excluded 18 million shares related to stock options, as the exercise price of these options was greater than their average market value. As of January 3, 2021, the Company did not have convertible debt.

The diluted net earnings per share calculation for fiscal year 2019 excluded an insignificant number of shares related to stock options, as the exercise price of these options was greater than the average market value of the Company’s stock. The diluted net earnings per share calculation for fiscal year 2019 included the dilutive effect of convertible debt that was offset by the related reduction in interest expense of $1 million after-tax.

The diluted net earnings per share calculation for fiscal year 2018 included all shares related to stock options, as the exercise price of all options was less than the average market value of the Company's stock. The diluted net earnings per share calculation for fiscal year 2018 included the dilutive effect of convertible debt that was offset by the related reduction in interest expense of $1 million after-tax.