NATURAL GAS SERVICES GROUP

Ticker: NGS CUSIP: 63886Q109 Class: Common Stock

Boston Trust Walden Corp's Holding History (CIK: 0001534866)

Note: Option positions (PUT/CALL) are excluded.

Q2 2019

Shares 217,569 Value ($000) $3,590 Avg Close $16.22 Range $14.71 - $18.54

Q1 2019

Shares 221,775 Value ($000) $3,839 Avg Close $17.65 Range $15.90 - $19.02

Q4 2018

Shares 214,848 Value ($000) $3,532 Avg Close $18.94 Range $15.26 - $20.99

Q3 2018

Shares 229,429 Value ($000) $4,841 Avg Close $21.85 Range $20.28 - $24.24

Q2 2018

Shares 239,680 Value ($000) $5,656 Avg Close $23.87 Range $21.47 - $26.42

Q1 2018

Shares 245,378 Value ($000) $5,852 Avg Close $26.44 Range $22.81 - $29.04

Q4 2017

Shares 263,228 Value ($000) $6,897 Avg Close $26.38 Range $23.89 - $29.04

Q3 2017

Shares 269,843 Value ($000) $7,664 Avg Close $24.49 Range $22.26 - $29.24

Q2 2017

Shares 273,358 Value ($000) $6,793 Avg Close $26.24 Range $22.26 - $28.69

Q1 2017

Shares 358,362 Value ($000) $9,336 Avg Close $27.74 Range $23.30 - $33.05

Q4 2016

Shares 385,950 Value ($000) $12,408 Avg Close $27.19 Range $20.43 - $34.13

Q3 2016

Shares 402,324 Value ($000) $9,893 Avg Close $24.06 Range $21.50 - $26.46

Q2 2016

Shares 403,375 Value ($000) $9,237 Avg Close $22.14 Range $19.61 - $25.27

Q1 2016

Shares 405,207 Value ($000) $8,765 Avg Close $18.82 Range $15.79 - $22.57

Q4 2015

Shares 408,563 Value ($000) $9,111 Avg Close $21.48 Range $18.28 - $24.21

Q3 2015

Shares 414,480 Value ($000) $8,000 Avg Close $20.31 Range $18.37 - $22.64

Q2 2015

Shares 422,167 Value ($000) $9,634 Avg Close $23.06 Range $19.10 - $25.82

Q1 2015

Shares 432,573 Value ($000) $8,314 Avg Close $19.65 Range $17.69 - $23.12

Q4 2014

Shares 440,462 Value ($000) $10,148 Avg Close $23.39 Range $20.44 - $26.73

Q3 2014

Shares 419,626 Value ($000) $10,101 Avg Close $28.91 Range $23.00 - $33.65

Q2 2014

Shares 433,695 Value ($000) $14,338 Avg Close $30.73 Range $28.13 - $34.48

Q1 2014

Shares 454,316 Value ($000) $13,693 Avg Close $29.49 Range $25.23 - $34.59

Q4 2013

Shares 463,491 Value ($000) $12,779 Avg Close $27.72 Range $24.44 - $30.62

Q3 2013

Shares 501,878 Value ($000) $13,460 Avg Close $25.86 Range $23.52 - $27.95

Q2 2013

Shares 515,353 Value ($000) $12,105 Avg Close $21.33 Range $18.17 - $23.75

Period	Shares	Value ($000)	Average Close	Price Range
Q2 2019	217,569	$3,590	$16.22	$14.71 - $18.54
Q1 2019	221,775	$3,839	$17.65	$15.90 - $19.02
Q4 2018	214,848	$3,532	$18.94	$15.26 - $20.99
Q3 2018	229,429	$4,841	$21.85	$20.28 - $24.24
Q2 2018	239,680	$5,656	$23.87	$21.47 - $26.42
Q1 2018	245,378	$5,852	$26.44	$22.81 - $29.04
Q4 2017	263,228	$6,897	$26.38	$23.89 - $29.04
Q3 2017	269,843	$7,664	$24.49	$22.26 - $29.24
Q2 2017	273,358	$6,793	$26.24	$22.26 - $28.69
Q1 2017	358,362	$9,336	$27.74	$23.30 - $33.05
Q4 2016	385,950	$12,408	$27.19	$20.43 - $34.13
Q3 2016	402,324	$9,893	$24.06	$21.50 - $26.46
Q2 2016	403,375	$9,237	$22.14	$19.61 - $25.27
Q1 2016	405,207	$8,765	$18.82	$15.79 - $22.57
Q4 2015	408,563	$9,111	$21.48	$18.28 - $24.21
Q3 2015	414,480	$8,000	$20.31	$18.37 - $22.64
Q2 2015	422,167	$9,634	$23.06	$19.10 - $25.82
Q1 2015	432,573	$8,314	$19.65	$17.69 - $23.12
Q4 2014	440,462	$10,148	$23.39	$20.44 - $26.73
Q3 2014	419,626	$10,101	$28.91	$23.00 - $33.65
Q2 2014	433,695	$14,338	$30.73	$28.13 - $34.48
Q1 2014	454,316	$13,693	$29.49	$25.23 - $34.59
Q4 2013	463,491	$12,779	$27.72	$24.44 - $30.62
Q3 2013	501,878	$13,460	$25.86	$23.52 - $27.95
Q2 2013	515,353	$12,105	$21.33	$18.17 - $23.75