All 10 global business centers now have vacancy rates below 10%, a milestone in the ongoing worldwide recovery of commercial real estate, according to the survey. Globalization of trade and borderless movement of money have allowed key cities to rebound in tandem relatively quickly from the real estate decline that followed the technology bust in 2000.

Hong Kong, which was hit by the dotcom collapse and suffered another blow after the SARS outbreak in 2003, has rebounded quickly and strongly. The city saw asking rents shoot up 37% in the past 12 months to an average of $69.12 per sf as the vacancy rate fell to 4.1%. And by mid-year Tokyo's vacancy rate of 0.6% was down from 2.2% and spurred a 12% jump in average asking rent to $148.17 per sf, according to the report.

London's asking rent rose 17% to an average of $163.23, and Madrid also logged a 17% increase, to a $43.18 average. London and Madrid vacancy stood at 5.7% and 8.2% respectively, at mid-year 2006. And in Paris, asking rents rose to $80 per sf, up 5.1%, while vacancy stood at 4.8%, down 0.7%.