CONCENTRATION OF RISK

12 Months Ended

Dec. 31, 2017

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):

	2017			2016			2015
Customer	% of Total Revenue	Accounts Receivable		% of Total Revenue	Accounts Receivable		% of Total Revenue	Accounts Receivable
A	62%	$	19,588	63%	$	12,050	62%	$	13,355
B	24%		17,348	28%		9,128	25%		8,477
C	6%		10,632	4%		1,427	1%		1,564

Revenues from outside of North America represented approximately 97%, 98%, and 99% of the consolidated revenue for the years ended December 31, 2017, 2016, and 2015, respectively. Revenues by geographic area are as follows (in thousands):

	Year Ended December 31,
Country	2017		2016		2015
South Korea	$	289,418	$	181,771	$	168,267
China		24,892		7,180		2,685
Japan		8,542		4,310		16,542
Other non-U.S. locations		2,438		1,849		2,334
Total non-U.S. locations		325,290		195,110		189,828
United States		10,339		3,776		1,218
Total revenue	$	335,629	$	198,886	$	191,046

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):

	2017		2016
United States	$	53,991	$	26,917
Other		2,459		286
Total long-lived assets	$	56,450	$	27,203

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