Our chief operating decision maker regularly reviews our financial performance based on two reportable segments – Network Solutions and Services & Support. Network Solutions includes software and hardware products and next-generation virtualized solutions used in service provider or business networks, as well as prior-generation products. Services & Support includes our suite of ProCloud managed services, network installation, engineering and maintenance services, and fee-based technical support and equipment repair/replacement plans.

We evaluate the performance of our segments based on gross profit. Selling, general, and administrative expenses, research and development expenses, interest and dividend income, interest expense, net investment gain (loss), other income (expense) and provision (benefit) for taxes are reported on a company-wide, functional basis only. There are no inter-segment revenues.

The following table presents information about the reported sales and gross profit of our reportable segments for each of the years ended December 31, 2018, 2017 and 2016. Asset information by reportable segment is not reported, since we do not produce such information internally.

	2018				2017				2016
(In thousands)	Sales		Gross Profit		Sales		Gross Profit		Sales		Gross Profit
Network Solutions	$	458,232	$	179,303	$	540,396	$	260,833	$	525,502	$	254,797
Services & Support		71,045		24,262		126,504		42,802		111,279		36,533
Total	$	529,277	$	203,565	$	666,900	$	303,635	$	636,781	$	291,330

In addition to the above reporting segments, we also report revenue for the following three categories – Access & Aggregation, Subscriber Solutions & Experience, and Traditional & Other Products.

The following tables disaggregates our revenue by major source for the years ended December 31, 2018, 2017 and 2016:

	2018
(In thousands)	Network Solutions		Services & Support		Total
Access & Aggregation	$	301,801	$	57,069	$	358,870
Subscriber Solutions & Experience ⁽¹⁾		129,067		5,393		134,460
Traditional & Other Products		27,364		8,583		35,947
Total	$	458,232	$	71,045	$	529,277

	2017
(In thousands)	Network Solutions		Services & Support		Total
Access & Aggregation	$	361,955	$	111,989	$	473,944
Subscriber Solutions & Experience ⁽¹⁾		132,294		6,162		138,456
Traditional & Other Products		46,147		8,353		54,500
Total	$	540,396	$	126,504	$	666,900

	2016
(In thousands)	Network Solutions		Services & Support		Total
Access & Aggregation	$	339,451	$	96,921	$	436,372
Subscriber Solutions & Experience ⁽¹⁾		130,645		6,963		137,608
Traditional & Other Products		55,406		7,395		62,801
Total	$	525,502	$	111,279	$	636,781

The following table presents sales information by geographic area for the years ended December 31, 2018, 2017 and 2016:

(In thousands)	2018		2017		2016
United States	$	288,843	$	508,178	$	501,337
Germany		167,251		119,502		85,780
Other international		73,183		39,220		49,664
Total	$	529,277	$	666,900	$	636,781

Customers comprising more than 10% of revenue can change from year to year. Single customers comprising more than 10% of our revenue in 2018 included two customers at 27% and 17%. Single customers comprising more than 10% of our revenue in 2017 included two customers at 40% and 16%. Single customers comprising more than 10% of our revenue in 2016 included three customers at 24%, 19% and 12%. Other than those with more than 10 percent of revenues disclosed above, and excluding distributors, our next five largest customers can change from year-to-year. These customers represented 18%, 15% and 13% of total revenue in 2018, 2017 and 2016, respectively.

As of December 31, 2018, long-lived assets, net totaled $80.6 million, which includes $77.3 million held in the U.S. and $3.3 million held outside the U.S. As of December 31, 2017, long-lived assets, net totaled $85.1 million, which includes $80.6 million held in the U.S. and $4.5 million held outside the U.S.