The table below sets forth the line items where share-based compensation expense was recorded for the twelve months ended December 31, 2018, 2017 and 2016:

	2018		2017		2016
Cost of goods sold	$	362	$	645	$	775
Selling, general and administrative expense		17,395		15,130		10,567
Research and development expense		2,979		2,834		2,687
Total share-based compensation expense	$	20,736	$	18,609	$	14,029

The table below sets forth share-based compensation expense by type for the twelve months ended December 31, 2018, 2017 and 2016:

	2018		2017		2016
Stock options	$	274	$	934	$	1,511
Share grants		20,462		17,675		12,518
Total share-based compensation expense	$	20,736	$	18,609	$	14,029

In 2016, we recorded a $2.7 million reversal of previously recorded expense related to performance grants.

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 $4.9 million, $13.6 million and $0.1 million during 2018, 2017 and 2016, respectively.

At December 31, 2018, 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, 2015		2,063		$	23.03
Exercised		(7	)		18.48
Forfeited or expired		(223	)		22.75
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		2.4	$	8,693
Exercisable at December 31, 2018		988			23.47		2.4	$	8,693

The table below sets forth information about stock options outstanding at December 31, 2018:

Plan

Range of exercise

prices

Number

exercisable

Weighted average

remaining

contractual life

(years)

Weighted average

exercise price

2001 Plan

15.05-29.21

678

2.2

22.48

2013 Plan

23.35-27.92

310

2.9

25.63

Share Grants – Restricted stock awards and restricted stock units generally vest in equal annual installments over a four-year period. Since the approval of the 2013 Plan, all new grants are granted under the 2013 Plan, and we will not grant any further grants under our 2001 Plan.

The table below sets forth a summary of our non-vested share grants in 2018, 2017 and 2016:

Restricted Stock Grants	Shares			Weighted Average Grant Date Fair Value ($)		Aggregate Intrinsic Value
Nonvested at December 31, 2015		2,679			23.51
Granted		880			18.63
Vested		(877	)		18.92
Forfeited		(62	)		20.80
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	$	53,396

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, 2018, was approximately $35.2 million, relating to restricted stock awards, which was expected to be recognized over a weighted average period of approximately 2.2 years.

Our Chief Executive Officer has a grant of 600,000 performance-based stock units that vest upon the Company reaching $1.0 billion in revenue. Based on the Company reaching approximately $1.1 billion in revenue in 2017, our Chief Executive Officer’s grant of 600,000 performance-based shares was released to the Chief Executive Officer, upon filing of the Company’s Annual Report on Form 10-K, in February 2018. The expense related to the 600,000 performance-based units was all recognized in previous periods.