The countries that experienced the largest unexplained increases in house prices were Ireland, the Netherlands, and the United Kingdom—by the end of the decade, house prices in these countries were about 30 percent higher than justified by fundamentals. A group of other countries, including France, Australia, and Spain, have house price gaps of about 20 percent. Based on this measure, the United States is among the middle-ranked countries in terms of vulnerability to a housing correction, partly reflecting the fact that U.S. house prices have already declined ...

The report covers a lot of ground, including the impact of changes in mortgage financing that made it easy for anyone to get a loan for just about any amount they wanted. Mortgage debt equaled about 75 percent of the United States' gross domestic product -- a key measure of economic activity -- in 2006, according to the IMF. In 1990, it was about 45 percent.