CONCENTRATION OF RISK

12 Months Ended

Dec. 31, 2021

19.

CONCENTRATION OF RISK:

Revenues and accounts receivable from the Company's largest customers for the years ended December 31, 2021, 2020 and 2019 were as follows (in thousands):


	2021			2020			2019
Customer	% of Total Revenue	Accounts Receivable		% of Total Revenue	Accounts Receivable		% of Total Revenue	Accounts Receivable
A	44%	$	10,850	41%	$	20,476	44%	$	13,830
B	26%		45,867	30%		26,776	27%		19,346
C	14%		18,557	13%		2,757	15%		10,592

Revenues from outside of North America represented approximately 97% of consolidated revenue for each of the years ended December 31, 2021, 2020 and 2019. Revenues by geographic area are as follows (in thousands):


	Year Ended December 31,
Country	2021		2020		2019
South Korea	$	334,835	$	263,079	$	250,562
China		192,079		142,076		135,259
Japan		7,358		7,405		5,276
Other non-U.S. locations		3,137		1,728		2,270
Total non-U.S. locations		537,409		414,288		393,367
United States		16,116		14,579		11,810
Total revenue	$	553,525	$	428,867	$	405,177

The Company attributes revenue to different geographic areas on the basis of the location of the customer.

Long-lived assets (net), by geographic area are as follows (in thousands):


	2021		2020
United States	$	115,004	$	93,230
Other		13,828		8,883
Total long-lived assets	$	128,832	$	102,113

Substantially all chemical materials were purchased from one supplier. See Note 13.