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Retirement Plans and Employee Stock Purchase Plans (Tables)
 12 Months Ended
Dec. 31, 2017
Retirement Plans and Employee Stock Purchase Plans  
Schedule of purchases made under the 2009 Employee Stock Purchase Plans

 

 

 

 

 

 

 

 

 

 

 

 

 

Year ended December 31,

 

 

 

2017

 

2016

 

2015

 

Number of shares purchased

    

 

88,362

    

 

151,531

    

 

254,098

 

Average price of shares purchased

 

$

33.96

 

$

20.87

 

$

13.50