15.	Share Plans

The Company adopted an equity incentive plan

(Plan) on

February

10,

2010

in connection with its initial public offering. The Plan, as amended, allows for granting of up to

9.1

million stock-based awards to executives, directors and employees. Awards available for grant under the Plan include stock options, stock appreciation rights, restricted stock, other stock-based awards and performance-based compensation awards. Total share-based compensation expense related to the Plan was

$9,493,

$8,241

and

$12,612

for the years ended

December

31,

2016,

2015

and

2014,

respectively, net of estimated forfeitures, which is recorded in operating expenses in the consolidated statements of comprehensive income.

Stock Options

- Stock options granted in

2016

have an exercise price between

$33.23

per share and

$35.37

per share; stock options granted in

2015

have an exercise price between

$28.36

per share and

$49.70

per share, and the stock options granted in

2014

have an exercise price between

$42.20

per share and

$59.01

per share.

Stock options issued in

2012

2016

vest in equal installments over

four

years, subject to the grantee’s continued employment or service and expire

ten

years after the date of grant. Stock options issued in

2011

and

2010

vest in equal installments over

five

years, subject to the grantee’s continued employment or service and expire

ten

years after the date of grant.

tock option exercises can be net-share settled such that the Company withholds shares with value equivalent to the exercise price of the stock option awards plus the employees’ minimum statutory obligation for the applicable income and other employment taxes. Total shares withheld were

473,743,

272,296

and

235,644

2016,

2015

and

2014,

respectively, and were based on the value of the stock on the exercise dates as determined based upon an average of the Company’s high and low stock sales price on the exercise dates. The net-share settlement has the effect of share repurchases by the Company as they reduce the number of shares that would have otherwise been issued.

Total payments for the employees' tax obligations to the taxing authorities were

$13,056,

$9,768

and

$10,411

2016,

2015

and

2014,

respectively, and are reflected as a financing activity within the consolidated statements of cash flows.

Employees can also utilize a cashless for cash exercise of stock options, such that all exercised shares will be sold in the market immediately. Cash equivalent to the exercise price of the awards plus the employees’ minimum statutory tax obligations is retained by the Company, with the remaining cash being transferred to the employee. Total proceeds from the cashless for cash exercise of stock options were

$1,623

2016,

and are reflected as a financing activity in the consolidated statement of cash flows.

The grant-date fair value of each option grant is estimated using the Black-Scholes-Merton option pricing model. The fair value is then amortized on a straight-line basis over the requisite service period of the awards, which is generally the vesting period. Use of a valuation model requires management to make certain assumptions with respect to selected model inputs.

Expected volatility is calculated based on an analysis of historic and implied volatility measures for a set of peer companies. The average expected life is based on the contractual term of the option using the simplified method. The risk-free interest rate is based on U.S. Treasury

zero

-coupon issues with a remaining term equal to the expected life assumed at the date of grant. The compensation expense recognized is net of estimated forfeitures. Forfeitures are estimated based on actual share option forfeiture history. The weighted-average assumptions used in the Black-Scholes-Merton option pricing model for

2016,

2015

and

2014

are as follows:

	201 6			201 5			201 4
Weighted average grant date fair value	$	13.77		$	19.07		$	26.35

Assumptions:
Expected stock price volatility		41	%		41	%		45	%
Risk free interest rate		1.31	%		1.72	%		1.90	%
Expected annual dividend per share	$	-		$	-		$	-
Expected life of options (years)		6.25			6.25			6.25

The Company periodically evaluates its forfeiture rates and updates the rates it uses in the determination of its stock-based compensation expense.

The impact of the change to the forfeiture rates on non-cash compensation expense was immaterial for the years ended

December

31,

2016,

2015

and

2014.

A summary of the Company

’s stock option activity and related information for the years ended

December

31,

2016,

2015

and

2014

is as follows:

	Number of Options			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term (in years)		Aggregate Intrinsic Value ($ in thousands)

Outstanding as of December 31, 2013		2,937,301		$	5.74		9.5	$	148,369
Granted		187,189			57.21
Exercised		(549,282	)		3.44
Expired		(259	)		15.94
Forfeited		(32,810	)		12.68
Outstanding as of December 31, 2014		2,542,139			9.94		8.5	$	96,518

Granted		287,165			45.18
Exercised		(604,088	)		3.79
Expired		(6,409	)		50.11
Forfeited		(90,793	)		37.27
Outstanding as of December 31, 2015		2,128,014			15.15		7.7	$	40,271

Granted		398,313			33.24
Exercised		(995,469	)		2.89
Forfeited		(47,894	)		37.41
Outstanding as of December 31, 2016		1,482,964			27.49		7.5	$	23,840

Exercisable as of December 31, 2016		787,654			17.64		6.7	$	19,897

As of

December

31,

2016,

there was

$8,051

of total unrecognized compensation cost, net of expected forfeitures, related to unvested options. The cost is expected to be recognized over the remaining service period, having a weighted-average period of

2.7

years. Total share-based compensation cost related to the stock options for

2016,

2015

and

2014

was

$4,366,

$4,198

and

$8,509,

respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income.

Restricted Stock

– Restricted stock awards issued in

2012

and after, vest in equal installments over

three

years, subject to the grantee’s continued employment or service. Certain restricted stock awards also include performance shares, which were awarded in the years

2014

through

2016.

The number of performance shares that can be earned are contingent upon Company performance measures over a

three

-year period. Performance measures are based on a weighting of revenue growth and EBITDA margin, from which grantees

may

earn from

200%

of their target performance share award. The performance period for the

2014

awards covers the years

2014

through

2016,

the performance period for the

2015

awards covers the years

2015

through

2017,

and the performance period for the

2016

awards covers the years

2016

through

2018.

The Company estimates the number of performance shares that will vest based on projected financial performance. The fair market value of the restricted awards at the time of the grant is amortized to expense over the period of vesting. The fair value of restricted awards is determined based on the market value of the Company's shares on the grant date. The compensation expense recognized for restricted share awards is net of estimated forfeitures.

Restricted stock

vesting is net-share settled such that, upon vesting, the Company withholds shares with value equivalent to the employees’ minimum statutory obligation for the applicable income and other employment taxes, and then pays those taxes on behalf of the employee. In effect, the Company repurchases these shares and classifies as treasury stock, and pays the cash to the taxing authorities on behalf of the employees to satisfy the tax withholding requirements. Total shares withheld were

28,593,

65,763

and

34,854

2016,

2015

and

2014,

respectively, and were based on the value of the stock on the vesting dates as determined based upon an average of the Company’s high and low stock sales price on the vesting dates. Total payments for the employees’ tax obligations to the taxing authorities were

$952,

$3,233

and

$1,770

2016,

2015

and

2014,

respectively, and are reflected as a financing activity within the consolidated statements of cash flows.

A summary of the Company's restricted stock activity for the years end

December

31,

2016,

2015

and

2014

is as follows:

	Shares			Weighted- Average Grant- Date Fair Value

Non-vested as of December 31, 2013		304,406		$	29.68
Granted		115,473			54.35
Vested		(105,123	)		28.31
Forfeited		(47,472	)		42.31
Non-vested as of December 31, 2014		267,284			38.72

Granted		193,117			41.31
Vested		(183,362	)		32.56
Forfeited		(33,999	)		47.77
Non-vested as of December 31, 2015		243,040			44.16

Granted		232,295			33.56
Vested		(95,858	)		41.93
Forfeited		(18,074	)		38.30
Non-vested as of December 31, 2016		361,403			38.18

As of

December

31,

2016,

there was

$7,192

of unrecognized compensation cost, net of expected forfeitures, related to non-vested restricted stock awards. That cost is expected to be recognized over the remaining service period, having a weighted-average period of

1.9

years.

Total share-based compensation cost related to the restricted stock for

2016,

2015

and

2014

was

$5,127,

$4,043

and

$4,103,

respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income.

During

201

2015

and

2014,

19,326,

16,260

and

8,869

shares, respectively, of fully vested stock were granted to certain members of the Company’s Board of Directors as a component of their compensation for their service on the Board. Total compensation cost for these share grants in

2016,

2015

and

2014

was

$670,

$615

and

$509,

respectively, which is recorded in operating expenses in the consolidated statements of comprehensive income.