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

	2019		2018		2017
Cost of goods sold	$	925	$	362	$	645
Selling, general and administrative expense		16,687		17,395		15,130
Research and development expense		2,923		2,979		2,834
Total share-based compensation expense	$	20,535	$	20,736	$	18,609

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

	2019		2018		2017
Stock options	$	-	$	274	$	934
Share grants		20,535		20,462		17,675
Total share-based compensation expense	$	20,535	$	20,736	$	18,609

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. No stock options were granted in any of the periods presented.

Total cash received from option exercises was approximately $11.9 million, $4.9 million and $13.6 million during 2019, 2018 and 2017, respectively.

At December 31, 2019, there was no unrecognized compensation expense related to unvested options.

Stock Options	Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Term (years)		Aggregate Intrinsic Value
Outstanding at December 31, 2016		1,833			23.08
Exercised		(581	)		23.42
Forfeited or expired		(24	)		26.87
Outstanding at December 31, 2017		1,228			22.85
Exercised		(240	)		20.28
Outstanding at December 31, 2018		988			23.47
Exercised		(524	)		22.68			$	10,600
Outstanding and Exercisable at December 31, 2019		464			24.37		2.0	$	14,849

The table below sets forth information about stock options outstanding at December 31, 2019:

Plan

Range of Exercise Prices

Number Exercisable

Weighted Average Remaining Contractual Life

(Years)

Weighted Average Exercise Price

2001 Plan

$15.05-29.21

259

2.0

23.17

2013 Plan

$23.35-27.92

205

2.0

25.91

Share Grants – Restricted stock awards and restricted stock units generally vest in equal annual installments over a four-year period. All new grants are granted under the 2013 Plan, and there will be no additional share grants under the 2001 Plan. 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 2019, 2018 and 2017:

Restricted and Performance Stock Grants	Shares			Weighted Average Grant Date Fair Value ($)		Aggregate Intrinsic Value
Nonvested at December 31, 2016		2,620			21.31
Granted		746			25.23
Vested		(645	)		21.89
Forfeited		(441	)		22.31
Nonvested at December 31, 2017		2,280			22.24
Granted		646			32.06
Vested		(1,213	)		21.39
Forfeited		(46	)		24.72
Nonvested at December 31, 2018		1,667			26.68
Granted		670			38.15
Vested		(573	)		24.90	$	20,682
Forfeited		(67	)		30.44
Nonvested at December 31, 2019		1,697			31.71	$	95,687

During 2017, the Company modified a performance-based award previously granted to our Chief Executive Officer. The effect was to replace a performance-based grant covering 700,000 shares of the Company’s common stock with a performance-based grant covering 62,905 shares of the Company’s common stock and a restricted stock grant covering 62,905 of the Company’s common stock. If certain performance criteria are met for the performance-based grant, Dr. Lu will receive 200% of that award or 125,810 shares. The incremental expense if Dr. Lu received 200% of the performance-based grant award is approximately $3.3 million. The incremental expense of the restricted stock grant is approximately $1.7 million. During 2018, we modified previously granted stock option and stock awards for two corporate officers who retired. The result of the modification was the acceleration of the vesting of 7,500 stock options and 79,720 stock awards for the corporate officers. The incremental expense recorded for this modification was approximately $1.8 million, which was expensed in SG&A during 2018.

The total unrecognized share-based compensation expense as of December 31, 2019, was approximately $40.0 million, relating to share grants, which was expected to be recognized over a weighted average period of approximately 2.2 years. The aggregate fair value amount of share grants that vested during 2019 was $20.7 million.