Exhibit 12.1

COMPUTATION OF RATIO OF EARNINGS TO FIXED CHARGES

(in thousands, except ratios; unaudited)

	Three Months Ended March 31,
	2018
Earnings:
Income before income taxes	$	6,359
Plus fixed charges deducted from income:
Interest expense	2,398
Amortization of debt financing fees	201
Implicit interest in rents	967
Total Earnings (x)	$	9,925
Fixed Charges:
Interest expense	2,398
Capitalized interest	146
Amortization of debt financing fees	201
Implicit interest in rents	967
Total Fixed Charges (y)	$	3,712
Ratio of Earnings to Fixed Charges(1)	2.7

	Year Ended December 31,
	2017		2016		2015		2014		2013
Earnings:
Income before income taxes	$	35,882	$	25,386	$	31,200	$	31,572	$	19,838
Plus fixed charges deducted from income:
Interest expense	7,736		8,798		6,229		8,829		8,044
Amortization of debt financing fees	685		952		987		987		845
Implicit interest in rents	3,437		3,089		2,884		2,179		1,488
Total Earnings (x)	$	47,740	$	38,225	$	41,300	$	43,567	$	30,216
Fixed Charges:
Interest expense	7,736		8,798		6,229		8,829		8,044
Capitalized interest	513		460		325		389		1,038
Amortization of debt financing fees	685		952		987		987		845
Implicit interest in rents	3,437		3,089		2,884		2,179		1,488
Total Fixed Charges (y)	$	12,371	$	13,299	$	10,425	$	12,385	$	11,416
Ratio of Earnings to Fixed Charges(1)	3.9		2.9		4.0		3.5		2.6

(1)The ratio of earnings to fixed charges is computed by dividing (x) total earnings by (y) fixed charges.