Regional environmental efficiency evaluation in China: Analysis based on the Super-SBM model with undesirable outputs

United States Energy Foundation project [G-1111-15134]; Ministry of Education, Philosophy and Social Planning project [12YJAZH056]; China Postdoctoral Science Foundation [20090460202]; National Natural Science Foundation of China [710201139]; Fundamental Research Funds for the Central Universities [2010221040]; National Bureau of Statistics Funds from China [2011LD002]