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, 2021 and 2020.

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 at the date of grant. The Company did not grant any stock option awards during the year ended December 31, 2021. The table below sets forth the assumptions used in the Black-Scholes pricing model for the year ended December 31, 2020.

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

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

	Year Ended
	December 31, 2021				December 31, 2020
	Number of Shares		Average Exercise Price		Number of Shares		Average Exercise Price
Options:
Outstanding, beginning of year		421,000	$	9.79		412,800	$	9.72
Granted		—		—		10,200		11.95
Exercised		750		8.23		666		10.75
Forfeited		—		—		1,334		9.70
Options outstanding, end of year		420,250	$	9.79		421,000	$	9.79
Options exercisable, end of year		395,678	$	9.74		359,413	$	9.62

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 $0.6 million as of December 31, 2021 and $0.2 million as of December 31, 2020.

During the years ended December 31, 2021 and 2020, respectively, 38,430 shares and 28,460 shares of restricted stock were granted. Awards granted to employees had a three-year vesting period, while awards granted to non-employee directors had a one-year vesting period. 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.