1. Graduate School of Economics, Kyoto University, Yoshida-Honmachi, Sakyo, Kyoto, Japan
2. Faculty of Economics, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, Japan
3. Center for Spatial Information Science, The University of Tokyo, 5-1-5, Kashiwanoha, Kashiwa, Chiba, Japan