The table below sets forth the line items where share-based compensation expense was recorded for the twelve months ended December 31:


	2021		2020		2019
Cost of goods sold	$	1,321	$	1,064	$	925
Selling, general and administrative expense		28,188		21,013		16,687
Research and development expense		3,696		3,183		2,923
Total share-based compensation expense	$	33,205	$	25,260	$	20,535

The table below sets forth share-based compensation expense by type for the twelve months ended December 31:


	2021		2020		2019
Stock options	$	73	$	-	$	-
Share grants		33,132		25,260		20,535
Total share-based compensation expense	$	33,205	$	25,260	$	20,535

In May 2013, our stockholders approved our 2013 Equity Incentive Plan (“2013 Plan”). Since the approval of the 2013 Plan, all stock options are granted under the 2013 Plan, and we will not grant any further stock options under our 2001 Plan. Stock options under the 2013 Plan generally vest in equal annual installments over a four-year period and expire eight years after the grant date. The number of shares originally authorized to be awarded under the 2013 Plan was 6 million shares. In May 2017, our stockholders approved an amendment to the 2013 Plan, authorizing and additional 6 million shares to be awarded, bringing the total shares authorized to be awarded under the 2013 Plan to 12 million shares.

Share-based compensation expense for stock options granted in previous years was calculated on the date of grant using the Black-Scholes-Merton option-pricing model. All stock option expense is related to stock options granted by Savitech Corporation (“Savitech”) in Savitech stock to their employees. We acquired a controlling interest in Savitech in 2020.

Total cash received from option exercises was approximately $4.3 million, $6.8 million and $11.9 million during 2021, 2020 and 2019, respectively.

At December 31, 2021, there was no unrecognized compensation expense related to unvested options.

The table below sets forth a summary of activity in our stock option plan:


Stock Options	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at December 31, 2018		988			23.47			$	8,693
Exercised		(524	)		22.68			$	10,600
Outstanding and Exercisable at December 31, 2019		464			24.37			$	14,849
Exercised		(272	)		25.11			$	8,278
Outstanding and Exercisable at December 31, 2020		192			23.32			$	9,059
Exercised		(187	)		23.19			$	10,631
Outstanding and Exercisable at December 31, 2021		5			27.92		0.4	$	409

The table below sets forth information about stock options outstanding at December 31, 2021:


Plan	Range of Exercise Prices		Number Exercisable		Weighted Average Remaining Contractual Life (Years)		Weighted Average Exercise Price
2013 Plan	$	27.92		5,000		0.4	$	27.92

Share Grants – Restricted stock awards and restricted stock units generally vest in equal annual installments over a four-year period. Restricted stock grants are measured based on the fair market value of the underlying stock on the date of grant and compensation expense is recognized on a straight-line basis over the requisite four-year service period.

Performance stock units (“PSUs”) are measured based on the fair market value of the underlying stock on the date of grant and compensation expense is recognized over the three-year performance period, with adjustments made to the expense to recognize the probable payout percentage. PSUs will vest upon the Company achieving a cumulative 3-year non-GAAP operating income target for the applicable periods.

The table below sets forth a summary of our non-vested share grants in 2020, 2019 and 2018:


Nonvested at December 31, 2018	1,667		26.68
Granted	670		38.15
Vested	(573	)	24.90
Forfeited	(67	)	30.44
Nonvested at December 31, 2019	1,697		31.71
Granted	573		48.83
Vested	(770	)	27.78
Forfeited and other	88		38.31
Nonvested at December 31, 2020	1,588		39.30
Granted	598		79.26
Vested	(750	)	33.39	$	60,346
Forfeited and other	(34	)	52.27
Nonvested at December 31, 2021	1,402		54.94	$	153,989

During 2020, in connection with the retirement of a member of the Company’s board of directors, the Company modified that director’s unvested RSU grants to vest upon his retirement. The shares subject to the modified grants will be released to that board member as if they were vesting under the original vesting timeline. In connection with this modification, the Company recorded additional expense of approximately $1.7 million.

The total unrecognized share-based compensation expense as of December 31, 2021, was approximately $59.1 million, relating to share grants, which was expected to be recognized over a weighted average period of approximately 2.2 years.