Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2016

The following table summarizes by repurchase plan the Company’s repurchasing activity:



	Cumulative shares repurchased	Average price per share
Non-Discretionary Plan (1994 through 2016)	33,674	$	29.92
Discretionary Plan (2001 through 2016)	57,710	$	40.57

The following table summarizes information about stock options:



	Number of shares		Weighted average exercise price per share		Weighted average remaining contractual life	Aggregate intrinsic value
Outstanding at December 31, 2015	18,732		$	43.39
Options granted	2,973		$	47.39
Options exercised	(3,732	)	$	42.17
Options forfeited	(351	)	$	43.48
Options canceled	(248	)	$	49.38
Outstanding at December 31, 2016	17,374		$	44.25	6.19	$	151,274
Exercisable at December 31, 2016	7,334		$	44.21	3.69	$	64,181

The fair value of each option grant is estimated on the date of grant using the Black-Scholes option pricing model with the following assumptions:



	For the years ended December 31,
	2016			2015			2014
Dividend yield	1.70		%	1.60		%	1.50 - 1.51%
Volatility – stock option plans	24 - 25%			29 - 34%			35 - 36%
Volatility – stock purchase rights plans	20		%	20		%	20		%
Risk-free interest rates	0.51 - 1.42%			0.30 - 2.04%			0.11 - 2.27%
Expected life (years) – stock option plans	5.5 - 6.5			6.41 - 7.47			6.52 - 7.43
Expected life (years) – stock purchase rights plans	1			1			1
Weighted average fair value of stock options granted during the period	$	9.57		$	13.44		$	14.44
Weighted average fair value of stock purchase rights granted during the period	$	10.99		$	10.45		$	9.60

Total stock compensation expense and the total related tax benefit recognized are as follows: