We account for our stock-based compensation plans using the fair value recognition provisions of ASC 718, Stock Compensation. Stock-based compensation is measured at the grant date, based on the calculated fair value of the award, net of an estimated forfeiture rate, and is recognized as an expense over the requisite employee service period (generally the vesting period of the grant). The estimated forfeiture rate is based on historical experience and revised, if necessary, in subsequent periods for actual forfeitures. There were 1,186,944 shares available for future stock-based payment awards under our 2016 Stock-Based Incentive Compensation Plan as of June 30, 2022.

The following table summarizes our non-vested stock activity for the six months ended June 30, 2022:


	Number of Shares			Weighted Average Grant Date Fair Value
Non-vested stock at December 31, 2021		480,147		$	25.56
Granted		15,376		$	41.63
Vested		(35,372	)	$	35.40
Forfeited		(38,594	)	$	29.37
Non-vested stock at June 30, 2022		421,557		$	24.97

As of June 30, 2022, we had unrecognized compensation expense of approximately $6.5 million related to non-vested stock that we expect to be recognized over a weighted-average period of approximately 1.4 years. The following table summarizes compensation expense related to non-vested stock, which is included in selling, general and administrative expenses in the accompanying condensed consolidated statements of income for the three and six months ended June 30, 2022 and 2021 (amounts in thousands):


	Three Months Ended				Six Months Ended
	June 30,				June 30,
	2022		2021		2022		2021
Compensation expense	$	1,311	$	943	$	2,989	$	2,543