CONCENTRATION OF RISK

12 Months Ended

Dec. 31, 2018

17.	CONCENTRATION OF RISK:

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

	2018			2017			2016
Customer	% of Total Revenue	Accounts Receivable		% of Total Revenue	Accounts Receivable		% of Total Revenue	Accounts Receivable
A	37%	$	14,419	62%	$	19,588	63%	$	12,050
B	33%		11,990	24%		17,348	28%		9,128
C	10%		9,071	6%		10,632	4%		1,427

Revenues from outside of North America represented approximately 94%, 97%, and 98% of the consolidated revenue for the years ended December 31, 2018, 2017 and 2016, respectively. Revenues by geographic area are as follows (in thousands):

	Year Ended December 31,
Country	2018		2017		2016
South Korea	$	171,915	$	289,418	$	181,771
China		51,931		24,892		7,180
Japan		6,823		8,542		4,310
Other non-U.S. locations		2,967		2,438		1,849
Total non-U.S. locations		233,636		325,290		195,110
United States		13,778		10,339		3,776
Total revenue	$	247,414	$	335,629	$	198,886

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):

	2018		2017
United States	$	64,560	$	53,991
Other		5,179		2,459
Total long-lived assets	$	69,739	$	56,450

Substantially all chemical materials were purchased from one supplier. See Note 11.