We operate in one line of business, which is operating hospitals and related health care entities. We operate in

two

geographically organized groups: the National and American Groups. At December 31, 2019, the National Group included 95 hospitals located in Alaska, California, Florida, southern Georgia, Idaho, Indiana, northern Kentucky, Nevada, New Hampshire, North Carolina, South Carolina, Utah and Virginia, and the American Group included 83 hospitals located in Colorado, northern Georgia, Kansas, southern Kentucky, Louisiana,

Mississippi, Missouri, Tennessee and Texas. We also operate six hospitals in England, and these facilities are included in the Corporate and other group.

Adjusted segment EBITDA is defined as income before depreciation and amortization, interest expense, gains on sales of facilities, losses on retirement of debt, income taxes and net income attributable to noncontrolling interests. We use adjusted segment EBITDA as an analytical indicator for purposes of allocating resources to geographic areas and assessing their performance. Adjusted segment EBITDA is commonly used as an analytical indicator within the health care industry, and also serves as a measure of leverage capacity and debt service ability. Adjusted segment EBITDA should not be considered as a measure of financial performance under generally accepted accounting principles, and the items excluded from adjusted segment EBITDA are significant components in understanding and assessing financial performance. Because adjusted segment EBITDA is not a measurement determined in accordance with generally accepted accounting principles and is thus susceptible to varying calculations, adjusted segment EBITDA, as presented, may not be comparable to other similarly titled measures of other companies. The geographic distributions of our revenues, equity in earnings of affiliates, adjusted segment EBITDA, depreciation and amortization, assets and goodwill and other intangible assets are summarized in the following table (dollars in millions):


	For the Years Ended December 31,
	2019			2018			2017
Revenues:
National Group	$	25,913		$	22,581		$	20,772
American Group		23,173			21,959			20,912
Corporate and other		2,250			2,137			1,930

	$	51,336		$	46,677		$	43,614

Equity in earnings of affiliates:
National Group	$	(2	)	$	(4	)	$	(21	)
American Group		(44	)		(40	)		(37	)
Corporate and other		3			15			13

	$	(43	)	$	(29	)	$	(45	)

Adjusted segment EBITDA:
National Group	$	5,634		$	4,980		$	4,600
American Group		4,904			4,593			4,231
Corporate and other		(681	)		(624	)		(598	)

	$	9,857		$	8,949		$	8,233

Depreciation and amortization:
National Group	$	1,161		$	946		$	867
American Group		1,117			1,027			986
Corporate and other		318			305			278

	$	2,596		$	2,278		$	2,131


	For the Years Ended December 31,
	2019			2018			2017
Adjusted segment EBITDA	$	9,857		$	8,949		$	8,233
Depreciation and amortization		2,596			2,278			2,131
Interest expense		1,824			1,755			1,690
Gains on sales of facilities		(18	)		(428	)		(8	)
Losses on retirement of debt		211			9			39

Income before income taxes	$	5,244		$	5,335		$	4,381


	December 31,
	2019		2018		2017
Assets:
National Group	$	18,290	$	14,839	$	13,097
American Group		20,608		19,122		18,136
Corporate and other		6,160		5,246		5,360

	$	45,058	$	39,207	$	36,593


	National Group			American Group			Corporate and Other			Total
Goodwill and other intangible assets:
Balance at December 31, 2016	$	1,458		$	4,661		$	585		$	6,704
Acquisitions		19			612			62			693
Foreign currency translation, amortization and other		(3	)		(8	)		8			(3	)

Balance at December 31, 2017		1,474			5,265			655			7,394
Acquisitions		132			504			—			636
Foreign currency translation, amortization and other		(9	)		(40	)		(28	)		(77	)

Balance at December 31, 2018		1,597			5,729			627			7,953
Acquisitions		155			39			138			332
F oreign currency translation, amortization and other		(13	)		(3	)		—			(16	)

Balance at December 31, 2019	$	1,739		$	5,765		$	765		$	8,269