16. Net loss per share attributable to common stockholders

The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders:

	Years ended December 31,
	2017			2016			2015
	(in thousands)
Numerator:
Net loss attributable to common stockholders, basic and diluted	$	(19,366	)	$	(27,331	)	$	(22,292	)
Denominator:
Weighted average number of common stock, basic and diluted		39,824			38,025			36,849
Net loss per share attributable to common stockholders:
Basic and diluted	$	(0.49	)	$	(0.72	)	$	(0.60	)

For the years ended December 31, 2017, 2016 and 2015, we excluded all assumed exercises of stock options and the assumed issuance of common stock under RSUs from the computation of diluted net loss per share as the effect would be anti-dilutive due to the net loss for the period.