Department of Statistics and Finance, University of Science and Technology of China, Hefei, 230026, China.|Department of Statistics and Finance, University of Science and Technology of China, Hefei, 230026, China.|Department of Statistics and Finance, University of Science and Technology of China, Hefei, 230026, China.|Department of Statistics and Finance, University of Science and Technology of China, Hefei, 230026, China.|Department of Statistics and Finance, University of Science and Technology of China, Hefei, 230026, China.