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Submitted on: 21 August 2010.
Revised on: 16 December 2010.
Accepted on: 01 January 2011.
___________________Applied Economic Perspectives and Policy
Submitted on: 21 September 2011.
Revised on: 26 November 2011.
Accepted on: 09 December 2011.
___________________Applied Economic Perspectives and Policy
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http://reply.papertrans.cn/1/22/2183/2183-35.png
Submitted on: 22 February 2016.
Revised on: 30 April 2016.
Accepted on: 24 May 2016.
___________________Applied Economic Perspectives and Policy