SHARE INCENTIVE PLAN (Tables)

12 Months Ended

Dec. 31, 2017

SHARE INCENTIVE PLAN

Summary of stock option activity

	Number		Weighted	Weighted average	Weighted average	Aggregate
	of options		average	grant-date	remaining contractual	intrinsic
	outstanding		exercise price	fair value per option	term (years)	value
Options outstanding at January 1, 2015	1,717,510		1.75	0.41	5.28
Granted	887,546		2.88	2.17
Forfeited	(38,800	)	1.52	0.34
Options outstanding at December 31, 2015	2,566,256		2.15	1.02	5.52	4,639
Forfeited	(29,300	)	1.76	0.41
Options outstanding at December 31, 2016	2,536,956		2.15	1.03	4.53	15,281
Granted	2,109,305		11.42	5.75
Exercised	(550,000	)	1.08	0.22
Forfeited	(17,000	)	2.32	0.79
Options outstanding at December 31, 2017	4,079,261		7.09	3.57	6.91	51,117
Options exercisable at December 31, 2017	2,638,379		4.59	2.24	5.50	43,585

Schedule of fair value assumptions

Grant date	November 5, 2015		June 22, 2017		July 1, 2017
Risk-free interest rate	2.26	%	2.15	%	2.31	%
Expected volatility	41	%	40	%	40	%
Expected dividend yield	0	%	0	%	0	%
Exercise multiples	2.8		2.8/2.2		2.8/2.2
Fair value of underlying ordinary share	3.84		11.67		11.67