(14)	Quarterly Results (Unaudited)

The unaudited quarterly results for the year ended December 31, 2018 were as follows (in thousands, except per share amounts):

	Three Months Ended
	March 31, 2018			June 30, 2018			September 30, 2018			December 31, 2018
Revenues	$	741,688		$	802,671		$	704,845		$	721,493
Costs and expenses		692,866			747,260			636,906			740,344
Gain (loss) on disposition of assets		1,898			442			18			(390	)
Operating income (loss)		50,720			55,853			67,957			(19,241	)
Other income		1,591			1,541			1,454			1,140
Interest expense		(9,780	)		(12,540	)		(12,345	)		(12,191	)
Earnings (loss) before taxes on income		42,531			44,854			57,066			(30,292	)
Benefit (provision) for taxes on income		(9,865	)		(16,061	)		(15,116	)		5,961
Net earnings (loss)		32,666			28,793			41,950			(24,331	)
Less: Net earnings attributable to noncontrolling interests		(195	)		(191	)		(134	)		(106	)
Net earnings (loss) attributable to Kirby	$	32,471		$	28,602		$	41,816		$	(24,437	)

Net earnings (loss) per share attributable to Kirby common stockholders:
Basic	$	0.54		$	0.48		$	0.70		$	(0.41	)
Diluted	$	0.54		$	0.48		$	0.70		$	(0.41	)

The unaudited quarterly results for the year ended December 31, 2017 were as follows (in thousands, except per share amounts):

	Three Months Ended
	March 31, 2017			June 30, 2017			September 30, 2017			December 31, 2017
Revenues	$	491,705		$	473,328		$	541,274		$	708,111
Costs and expenses		445,760			425,937			488,186			756,423
Gain (loss) on disposition of assets		99			(139	)		(159	)		(4,288	)
Operating income (loss)		46,044			47,252			52,929			(52,600	)
Other income (expense)		(589	)		228			320			902
Interest expense		(4,457	)		(4,465	)		(5,388	)		(7,162	)
Earnings (loss) before taxes on income		40,998			43,015			47,861			(58,860	)
Benefit (provision) for taxes on income		(13,353	)		(17,043	)		(19,072	)		290,357
Net earnings		27,645			25,972			28,789			231,497
Less: Net earnings attributable to noncontrolling interests		(162	)		(194	)		(182	)		(178	)
Net earnings attributable to Kirby	$	27,483		$	25,778		$	28,607		$	231,319

Net earnings per share attributable to Kirby common stockholders:
Basic	$	0.51		$	0.48		$	0.52		$	3.88
Diluted	$	0.51		$	0.48		$	0.52		$	3.87

Quarterly basic and diluted earnings per share may not total to the full year per share amounts, as the weighted average number of shares outstanding for each quarter fluctuates as a result of the assumed exercise of stock options.