GRIPS Policy Information Center Discussion Paper : 08-16 1 1 20 12 18 2 1998 1997 1975 2007 0.87 3 1998 1 2008 11 12 2 106-8677 7-22-1 , e-mail: susumukuwahara@grips.ac.jp, tel: 03-6439-6143, fax: 03-6439-6010. 3 (2008) GRIPS Policy Information Center Discussion Paper : 08-16 2 2003 1998 (2008) (p98 99) 4 4 2007 6 30 GRIPS Policy Information Center Discussion Paper : 08-16 3 2006 18 85 2007 Yang a