Exhibit 12.1

Statement Regarding Computation of Ratio of Earnings to Fixed Charges

The following table sets forth our ratio of earnings to fixed charges for the three months ended March 31, 2018 and 2017 and for the years ended December 31, 2017, 2016, 2015, 2014 and 2013.

	Three Months Ended March 31,						Year Ended December 31,
(Dollars in thousands)	2018			2017			2017			2016			2015			2014			2013
Earnings	$	32,296		$	17,161		$	117,806		$	93,118		$	70,767		$	33,530		$	19,679
Fixed charges	$	13,587		$	7,888		$	46,469		$	27,371		$	20,693		$	11,053		$	1,183
Ratio of earnings to fixed charges		2.38			2.18			2.54			3.40			3.42			3.03			16.63
Earnings (Loss):
Income before income taxes	$	23,107		$	12,051		$	84,164		$	73,149		$	60,305		$	30,959		$	18,073
Add: fixed charges		13,587			7,888			46,469			27,371			20,693			11,053			1,183
Less: capitalized interest		(13,357	)		(7,734	)		(45,725	)		(26,904	)		(20,313	)		(10,848	)		(1,098	)
Add: amortization of previously capitalized interest		8,959			4,956			32,898			19,502			10,082			2,366			1,521
Total earnings	$	32,296		$	17,161		$	117,806		$	93,118		$	70,767		$	33,530		$	19,679
Fixed Charges:
Interest expense (1)	$	2		$	1		$	(3	)	$	5		$	10		$	26		$	—
Interest component of rent expense		228			153			747			462			370			179			85
Capitalized interest		13,357			7,734			45,725			26,904			20,313			10,848			1,098
Total fixed charges	$	13,587		$	7,888		$	46,469		$	27,371		$	20,693		$	11,053		$	1,183

⁽¹⁾ Excludes capitalized interest.