Of the 176 cities CBRE tracked, 133 saw occupancy costs dip. Roughly 33 markets registered double-digit percentage point declines, while 53 markets—smaller ones impacted by shifts in key market assets—witnessed annual increases, according to the survey.

So how does this reflect on the much-touted global recovery? If rates are still dwindling in a number of major markets, what does that say about the rebound? "Commercial real estate lags the economy," CBRE's chief global economist, Raymond Torto, reminded participants on this morning's conference call announcing the survey results. "A lot of the decline we tracked occurred in the first couple of months of 2009," but the rates will likely continue to bottom out this year, he noted.

But all hope is not lost, chimed in Michael Haddock, director of CBRE's Global Research and Consulting. "Within a year or two, there will be rental growth in prime office space," he said. Historical trends have shown, he added, that economic recover is followed by employment growth, then occupancy and finally rental growth.

Some markets have been quite capable of maintaining strong—if not exorbitant—office rents. London's West End certainly retained its title as the world's most expensive office market, with an occupancy cost of $182.94 per square foot.

"In the past two quarters, we've been seeing an uptick in rent in London," said Haddock, who also heads CBRE's EMEA regional real estate investment market research team. He noted, however, that, "Only the best areas of the city are seeing strong rents, which is driven by the fact that the financial district is performing well."

Currency fluctuations, according to Torto, played a significant role in determining which markets had the highest office costs. Rates measured in US dollars were impacted by changes in the value of the dollar versus the respective currency. In spite of recent depreciation of the British pound, for instance, it still holds more weight than the dollar.

Overall, Europe, the Middle East and Africa, or the EMEA region, continues to contain the wealth, 29 in total, of the top 50 most expensive markets. Paris and Dubai, for instance, continue to post rents well above $100 per square foot. And Moscow rounded out the top five priciest markets, collecting average rents of $125.10 per square foot—down 26.5% from the previous period, however. Indeed, the EMEA region experienced an annual decline of 6.2%, with rental rate drops in 44 of its 57 markets.

Meanwhile, the Asia Pacific region boasted three of the top five most expensive markets. Hong Kong, with an average $153.20 per square foot, ranked second, pushing Tokyo to the third spot, with rents penciling in $143.99 per square foot. Mumbai, with office occupancy costs of $125.76 per square foot, moved up to fourth place, thanks largely to the appreciation of the Rupee to the dollar.

Despite seeing some gains in rates, Asia-Pacific witnessed the largest collective decline in occupancy costs with a drop of 9.2%. Still, several Asian markets are experiencing a rebound in rents, as demand for office space improved in the first few months of this year.

North America posted a below average decline of 3.3% year-over-year, making the region the third weakest with rising vacancy in 51 out of its 77 markets. Further south of the equator, the Latin American market—predictably led by Brazil—was the only region to log an increase in year-over-year office rates.

Torto pointed out that Brazil, whose economy continues to be a major growth engine, has a bifurcated office market that offers investment opportunities. "There is quite a bit of prime office space in Brazil," he said. "But about 40% of Brazilian office in Rio de Janerio and Sao Paulo is without air condition. So there is a scurry of activity to develop class A office.