REVENUE BY GEOGRAPHIC AREA, MAJOR CUSTOMERS AND SEGMENT INFORMATION

Revenue by customer location, including customers in a foreign country representing 10% or more of total revenue, follows:



	Year Ended December 31,
($ millions)	2017		2016

United States	$	134.5	$	242.8
Foreign:
Japan	49.0		49.1
Belgium	34.9		—
Other	—		19.4
	83.9		68.5
Total revenue	$	218.4	$	311.3

In 2017, our 10 largest customers represented approximately 97% of total revenue and our four largest customers represented approximately 53% of total revenue. In our LEU segment, revenue from Synatom, Entergy, American Electric Power and South Carolina Electric & Gas represented approximately 16%, 14%, 12% and 11%, respectively, of total revenue in 2017. In 2016, our 10 largest customers represented approximately 90% of total revenue and our four largest customers represented approximately 50% of total revenue. In our LEU segment, revenue from Exelon Corporation, South Carolina Electric & Gas and American Electric Power represented approximately 15%, 12% and 11%, respectively, of total revenue in 2016. In our contract services segment, the U.S. government and its contractors represented approximately 11% of total revenue in 2017 and 12% of total revenue in 2016. No other customer represented more than 10% of total revenue in 2017 or 2016.

Centrus has two reportable segments: the LEU segment with two components, SWU and uranium, and the contract services segment. The LEU segment includes sales of the SWU component of LEU, sales of both the SWU and uranium components of LEU, and sales of uranium. The contract services segment includes revenue and cost of sales for work that Centrus performs under a fixed price agreement as a contractor to UT-Battelle. The contract services segment also includes limited services provided by Centrus to DOE and its contractors at the Piketon facility. Gross profit is Centrus’ measure for segment reporting. There were no intersegment sales in the periods presented.

The Company’s revenue and gross profit by segment are as follows:



	Year Ended December 31,
($ millions)	2017			2016

Revenue
LEU segment:
Separative work units	$	195.4		$	258.5
Uranium	—			14.3
	195.4			272.8
Contract services segment	23.0			38.5
Revenue	$	218.4		$	311.3

Segment Gross Profit
LEU segment	$	59.3		$	38.5
Contract services segment	(2.5		)	6.6
Gross profit	$	56.8		$	45.1

The Company’s assets by segment are as follows:



	December 31,
($ millions)	2017		2016

Assets
LEU segment	$	657.4	$	686.0
Contract services segment	17.9		27.5
	$	675.3	$	713.5

Centrus’ long-term or long-lived assets, which include property, plant and equipment and other assets reported on the consolidated balance sheet, were located in the United States as of December 31, 2017, and December 31, 2016.