Item 6. SELECTED FINANCIAL DATA

	Year Ended December 31,
(In thousands, except per share amounts)	2019			2018			2017		2016		2015
Operating Data:
Revenue from operations	$	4,109,111		$	4,043,695		$	3,358,112	$	2,991,517	$	2,972,442
Depreciation and amortization expense		253,681			230,357			205,763		189,867		165,343
Total operating expenses		3,290,405			3,226,644			2,782,226		2,507,682		2,474,202
Operating income		818,706			817,051			575,886		483,835		498,240
Interest (income) expense, net		(6,386	)		(2,924	)		1,414		4,274		5,001
Provision for income taxes		208,431			209,845			112,058		181,822		185,327
Net income (1)		615,518			605,668			463,774		295,765		304,690

Per Share Data:
Basic earnings per share	$	7.67		$	7.39		$	5.63	$	3.56	$	3.57
Diluted earnings per share	$	7.66		$	7.38		$	5.63	$	3.56	$	3.57
Cash dividends per share	$	0.68		$	0.52		$	0.40	$	—	$	—

Balance Sheet Data:
Cash and cash equivalents	$	403,571		$	190,282		$	127,462	$	10,171	$	11,472
Current assets		866,834			706,229			584,653		382,622		381,730
Total assets (2)		3,995,568			3,545,283			3,068,424		2,696,247		2,466,504
Current liabilities (2)		366,085			356,732			351,049		288,636		285,402
Long-term debt (including current maturities)		45,000			45,000			95,000		104,975		133,805
Shareholders’ equity		3,080,717			2,680,483			2,276,854		1,851,158		1,684,637

(1)	Our 2017 net income included a tax benefit of $104.9 million due to the remeasurement of our deferred taxes to reflect the impact of the Tax Act.

(2)	On January 1, 2019, the Company adopted Accounting Standards Update 2016-02, “Leases” (Topic 842), which resulted in the recognition of right-of-use assets of approximately $65 million with corresponding lease liabilities on our Balance Sheet as of December 31, 2019.