This is residential investment in the United States as a fraction of GDP.

美国国内生产总值的一部分,就是住宅投资

耶鲁公开课 - 金融市场课程节选

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