Potential common shares are excluded from the diluted net income per share computation to the extent that they would be antidilutive. If the Company reported a net loss for the year, no potentially dilutive securities would be included in the computation of diluted net loss per share. As discussed in Note 11, Debt, the Company has the option to pay cash for the aggregate principal amount due upon the conversion of its 2025 Notes, and intends to do so.

ASU 2020-06 was adopted on January 1, 2022 and requires the Company to use the if-converted method to calculate the number of potentially dilutive shares for convertible debt. Under the if-converted method, adjustments are made to the diluted net income per common share calculation as if the Company had converted the convertible debt on the first day of each period presented. Adjustments to the numerator are made to add back the interest expense associated with the convertible debt on a post-tax basis. Adjustments to the denominator reflect the number of shares assumed to be convertible at the beginning of the period. For additional information regarding the adoption of ASU 2020-06, see Note 3, Recent Accounting Pronouncements. For the years ended December 31, 2021 and 2020, the Company used the treasury stock method to calculate dilutive shares on its convertible debt.

The following table sets forth the computation of basic and diluted net income per common share for the years ended December 31, 2022, 2021 and 2020 (in thousands, except per share amounts):


	Year Ended December 31,
	2022		2021		2020
Numerator:
Net income—basic	$	15,909	$	41,980	$	145,523





Denominator:
Weighted average common shares outstanding—basic	45,521		44,262		42,671
Computation of diluted securities:

Dilutive effect of stock options	787		1,030		783
Dilutive effect of RSUs	226		298		227
Dilutive effect of conversion premium on the 2022 Notes	—		38		—
Dilutive effect of ESPP purchase options	4		2		1
Weighted average common shares outstanding—diluted	46,538		45,630		43,682
Net income per share:
Basic net income per common share	$	0.35	$	0.95	$	3.41
Diluted net income per common share	$	0.34	$	0.92	$	3.33

The following table summarizes the outstanding stock options, RSUs, ESPP purchase options and convertible senior notes that were excluded from the diluted net income per common share calculation because the effects of including these potential shares were antidilutive in the periods presented (in thousands):


	Year Ended December 31,
	2022	2021	2020
Weighted average number of stock options	2,821	2,141	4,237
Convertible senior notes (1)	6,206	—	—
Weighted average number of RSUs	417	116	99
Weighted average ESPP purchase options	7	13	16
Total	9,451	2,270	4,352

(1) The convertible senior notes were antidilutive for the year ended December 31, 2022, in conjunction with a $5.1 million if-converted method adjustment to the numerator that adds back the interest expense associated with the convertible debt on a post-tax basis under ASU 2020-06.