1. School of Economics and Management, Qilu Normal University, Jinan 250200, China
2. School of Insurance, Southwestern University of Finance and Economics, Chengdu, Sichuan 611130, China
3. School of Finance, Zhongnan University of Economics and Law, Wuhan, Hubei 430073, China
4. School of Insurance, Shandong University of Finance and Economics, Jinan, Shandong 250014, China