First Author:   Ryo Horii Osaka University horii@econ.osaka-u.ac.jp   Graduate School of Economics, Osaka University, 1-7 Machikaneyama Toyonaka, 560-0043, Japan   06-6850-5254(Phone) 06-6850-5254(Fax) Second Author: Koichi Futagami Osaka University futagami@econ.osaka-u.ac.jp   Graduate School of Economics, Osaka University, 1-7 Machikaneyama Toyonaka, 560-0043, Japan   06-6850-5266(Phone) 06-6850-5256(Fax) Third Author: Akiomi Kitagawa Tohoku University kitagawa@econ.tohoku.ac.jp   Graduate School of Economics and Management, Tohoku University, 27-1 Kawauchi, Aoba-ku Sendai, 980-8576, Japan   022-217-6326(Phone) 022-217-6326(Fax)