"It would double the public debt in five years, triple it in ten years - the highest percentage of GDP since after World War II.

VOA: standard.2009.03.22

You can see that residential investment, as a fraction of GDP, has been very variable through history of the United States since World War II and that it's had a strong relationship with recessions.

住宅投资要计入,国内生产总值,纵观美国自二战以来,这部分投资,变动很大,而且与衰退存在着密切关联

耶鲁公开课 - 金融市场课程节选