In accordance with the 2013 Incentive Plan, stock awards, including stock options and restricted stock, have been granted to certain employees and non-employee directors. Shares of common stock available for distribution to satisfy the grants may consist, in whole or in part, of authorized and unissued shares, treasury shares or shares reacquired by the Company in any manner. Stock-based compensation expense related to stock awards totaled $0.3 million for each of the years ended December 31, 2020 and 2019.

Stock option awards have been granted with an exercise price equal to the market price of the Company’s common stock on the date of the grant and have vesting periods ranging from one to three years, with 10-year contractual terms.

The Company recognizes the cost of services received in exchange for stock option awards based on the grant date fair value of the award, with compensation expense recognized on a straight-line basis over the award’s vesting period. The fair value of outstanding awards was determined using the Black-Scholes option pricing model based on the assumptions noted in the table below. Expected volatilities are based on historical volatilities of the Company’s common stock.

	2020			2019
Risk-free interest rate		1.24	%		2.59	%
Expected term (in years)		7.5			7.5
Expected stock price volatility		28.9	%		30.9	%
Dividend yield		1.25	%		1.25	%
Fair value of stock option	$	3.34		$	3.30

The following table summarizes the Company’s stock option activity for the periods presented.

	Year Ended
	December 31, 2020				December 31, 2019
	Number of Shares		Average Exercise Price		Number of Shares		Average Exercise Price
Options:
Outstanding, beginning of year		412,800	$	9.72		377,950	$	9.80
Granted		10,200		11.95		68,150		9.99
Exercised		666		10.75		7,000		8.30
Forfeited		1,334		9.70		26,300		11.96
Options outstanding, end of year		421,000	$	9.79		412,800	$	9.72
Options exercisable, end of year		359,413	$	9.62		298,467	$	9.16

The aggregate intrinsic value of stock options outstanding (calculated as the amount by which the market value of underlying stock exceeds the exercise price of the option) was approximately $0.2 million as of December 31, 2020 and $0.9 million as of December 31, 2019.

During the years ended December 31, 2020 and 2019, respectively, 28,460 shares and 5,520 shares of restricted stock were granted. The Company recognizes the cost of services received in exchange for restricted stock awards based on the grant date closing price of the stock, with compensation expense recognized on a straight-line basis over the award’s vesting period.