This presumes that the economic structures of these countries are sufficiently alike that any shocks will be felt by all of them at roughly the same time and to a similar degree. A good number of the euro countries probably fall into this category.
Toshihiko Fukui: Islamic finance – developments, diversity and challenges Opening remarks by Mr Toshihiko Fukui, Governor of the Bank of Japan, at the Nikkei Islamic Finance Symposium 2008: "Islamic Finance: Constant Evolution and Emerging Opportunities", Tokyo, 23 February 2008.