Much of the global rental growth can be seen in Asia, led by India and China. "China is a strong growth area," CBRE's chief economist Steven Dunn tells GlobeSt.com. "And it's growing so fast in the office services sector."

With a 69% increase in occupation costs in the last 12 months, Mumbai's Nariman Point submarket has seen the greatest rent appreciation. At $93 per sf, the area broke into the top 10 most expensive markets. India, Dunn points out, is populated by more than just call service centers. "There is a middle class that needs to be serviced." Dunn adds that legislative changes expected this year could bring about a lot of development opportunities for foreign investment. "That demand for space is not going to go away soon." Elsewhere in Asia, Hong Kong occupancy costs jumped 50% to $102 over the last year.

London's West End remains the world's most highly priced business district at $186 per sf. Occupancy costs are up 10% since last year and are 30% higher than the next most expensive submarket.