NATURAL GAS SERVICES GROUP

Ticker: NGS CUSIP: 63886Q109 Class: Common Stock

GREAT LAKES ADVISORS, LLC's Holding History (CIK: 0001078013)

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

Q3 2014

Shares 203,169 Value ($000) $4,890 Avg Close $28.91 Range $23.00 - $33.65

Q2 2014

Shares 87,728 Value ($000) $2,900 Avg Close $30.73 Range $28.13 - $34.48

Q1 2014

Shares 110,189 Value ($000) $3,321 Avg Close $29.49 Range $25.23 - $34.59

Q4 2013

Shares 53,448 Value ($000) $1,473 Avg Close $27.72 Range $24.44 - $30.62

Q3 2013

Shares 26,721 Value ($000) $717 Avg Close $25.86 Range $23.52 - $27.95

Q2 2013

Shares 11,173 Value ($000) $263 Avg Close $21.33 Range $18.17 - $23.75

Period	Shares	Value ($000)	Average Close	Price Range
Q3 2014	203,169	$4,890	$28.91	$23.00 - $33.65
Q2 2014	87,728	$2,900	$30.73	$28.13 - $34.48
Q1 2014	110,189	$3,321	$29.49	$25.23 - $34.59
Q4 2013	53,448	$1,473	$27.72	$24.44 - $30.62
Q3 2013	26,721	$717	$25.86	$23.52 - $27.95
Q2 2013	11,173	$263	$21.33	$18.17 - $23.75