. Share-based payments

(a)

Stock options

The fair value of each option grant is estimated on the date of grant using the Black-Scholes option-pricing model, consistent with the guidance on stock compensation. Because option-pricing models require the use of subjective assumptions, changes in these assumptions can materially affect the fair value of the options. The assumptions presented in the table below represent the weighted average of the applicable assumption used to value stock options at their grant date. The Company calculates expected volatility based on historical volatility of the Company's common shares. The expected term, which represents the period of time that options granted are expected to be outstanding, is estimated based on historical exercise experience. The Company evaluated historical exercise behavior when determining the expected term assumptions. The risk-free rate assumed in valuing the options is based on the U.S. Treasury yield curve in effect at the time of grant for the expected term of the option. The Company determines the expected dividend yield percentage by dividing the expected annual dividend by the market price of our common shares at the date of grant.

Details of stock option transactions for

the

three

months ended

September 30, 2017

and

September 30, 2016

are as follows:

	Three months ended September 30,					Three months ended September 30,
	2017					2016
	Number of shares			Weighted average exercise price per share		Number of shares			Weighted average exercise price per share

Outstanding, beginning of period		363,608		$	16.79		502,590		$	11.30
Granted		327,150			55.49		18,750			27.53
Exercised		(30,051	)		6.67		(31,065	)		38.00
Forfeited		(1,050	)		51.87		-			-
Expired		-			-		-			-
Outstanding, end of period		659,657			36.39		490,275			12.39
Options exercisable, end of period		223,043		$	14.30		306,553		$	9.16

Details of stock option transactions for the

nine

months ended

September 30, 2017

and

September 30, 2016

are as follows:

	Nine months ended September 30,					Nine months ended September 30,
	2017					2016
	Number of shares			Weighted average exercise price per share		Number of shares			Weighted average exercise price per share

Outstanding, beginning of period		474,501		$	12.67		513,366		$	9.24
Granted		360,025			54.13		81,750			22.66
Exercised		(165,673	)		7.79		(94,602	)		3.75
Forfeited		(9,196	)		22.08		(9,489	)		17.23
Expired		-			-		(750	)		3.76
Outstanding, end of period		659,657			36.39		490,275			12.39
Options exercisable, end of period		223,043		$	14.30		306,553		$	9.16

As of

September 30, 2017,

the exercise prices, weighted average remaining contractual life and intrinsic values of outstanding options were as follows:

			Options outstanding								Options exercisable
Exercise price			Number outstanding		Weighted average exercise price per share		Weighted average remaining contractual life (years)		Aggregate intrinsic value		Number exercisable		Weighted average exercise price per share		Weighted average remaining contractual life (years)		Aggregate intrinsic value

$ 2.92	-	$ 8.92		96,644	$	6.72		1.9	$	5,008,805		96,644	$	6.72		1.9	$	5,008,805
$10.16	-	$19.95		122,938		16.29		3.7		5,195,152		76,399		15.99		3.5		3,251,248
$21.10	-	$27.53		81,000		23.65		4.4		2,826,893		45,000		25.39		3.7		1,492,313
$35.25	-	$37.35		14,375		35.89		5.7		325,750		5,000		35.25		6.2		116,500
$43.15	-	$47.00		18,500		44.19		6.3		265,650		-		-		-		-
$53.55	-	$55.65		326,200		55.49		6.7		998,480		-		-		-		-
				659,657	$	36.39		5.1	$	14,620,730		223,043	$	14.30		2.9	$	9,868,866

Total unrecognized compensation

cost relating to unvested stock options at

September 30, 2017

was approximately

$7.0

million and is expected to be recognized over a weighted average period of

3.1

years.

The Company recorded stock-based

compensation of

$0.2

million and

$0.8

million for the

three

and

nine

months ended

September 30, 2017

and

$0.2

million and

$0.6

million for the

three

and

nine

months ended

September 30, 2016,

respectively.

The Company has

not

capitalized any stock-based compensation expense as part of the cost of an asset.