Table:
2015	2016	2017	20181	2019

Net Income	$672	$970	$1,225	$1,265	$1,917

Income tax provision (benefit)	158	156	31	(110)	(0)

Other expense (income)	135	48	(31)	(24)	(18)

Loss (gain) on retirement of long-term obligations	80	(1)	70	3	22

Interest expense	596	717	750	826	814

Interest income	(17)	(26)	(35)	(55)	(47)

Other operating expenses	67	73	256	513	166

Depreciation, amortization and accretion	1,285	1,526	1,716	2,111	1,778

Stock-based compensation expense	91	90	109	138	111

ADJUSTED EBITDA	$3,067	$3,553	$4,090	$4,667	$4,745

Divided by total revenue	$4,772	$5,786	$6,664	$7,440	$7,580

ADJUSTED EBITDA MARGIN	64%	61%	61%	63%	63%

Answer the following question taking into account the given table and text, produce your answer and, if helpful, briefly explain your calculation. Conclude with JSON: {"answer": ["ANSWER"], "scale": "SCALE"} ("scale" = "" if no unit).

Background:
American Tower Corporation • 2019 Annual Report
Appendix 1 • Letter to Stakeholders
RECONCILIATION OF ADJUSTED EBITDA TO NET INCOME ($ in millions. Totals may not add due to rounding.)

Question: What was the percentage change in Interest expense between 2015 and 2016?

((717-596)/596) * 100, therefore {"answer": "20.3", "scale": "percent"}