Earnings per Share

The weighted average common shares used in the computations of basic and diluted earnings per share (shares in thousands) for the years ended September 30 were as follows:



	2018	2017	2016
Average common shares outstanding	258,354	218,943	212,702
Dilutive share equivalents from share-based plans (a) (b)	6,267	4,645	4,834
Average common and common equivalent shares outstanding — assuming dilution	264,621	223,588	217,536

(a)

For the years ended September 30, 2018 and 2017, dilutive share equivalents associated with mandatory convertible preferred stock of 12 million and 5 million, respectively, were excluded from the diluted shares outstanding calculation because the result would have been antidilutive. The issuance of the convertible preferred stock is further discussed in Note 3. For the years ended September 30, 2018, 2017 and 2016, there were no options to purchase shares of common stock which were excluded from the diluted earnings per share calculation.


(b)	The adjustment to calculate diluted share equivalents from share-based plans in 2016 included excess tax benefits relating to share-based compensation awards. Upon the Company's adoption, as discussed in Note 2, of new accounting requirements relating to share-based compensation award-related income tax effects, the adjustments in 2018 and 2017 excluded these excess tax benefits.