Office rental rates in Austin increased 13.2 percent year-over-year in July, August and September, according to data released Oct. 20 from Cushman & Wakefield/Oxford Commercial.

Rental rates in the third quarter of 2015 averaged $33.02 per square foot, according to CWOC, up from $29.17 during the same time last year. Class A office space—space deemed to be the best in market—in downtown Austin’s central business district increased the highest to $48.07 per square foot, an 11.5 percent year-over-year increase.

CWOC data shows more office space—1.8 million square feet—has become available so far in 2015 than all of last year when 1.7 million square feet of office space came online.

“There’s a very high level of demand by office tenants to locate and grow in Austin, and the office sector continues to feel it,” said Rick Whiteley, CWOC partner, in a statement. “Developers continue to respond with lots of new product, and tenants continue to absorb the new supply.”

Overall, only 9 percent of Austin-area office space is vacant, according to CWOC data, despite 3.1 million square feet of new space recently completed or under construction.

Most vacancies are found in the area’s southeast sector, where 22.3 percent of office space went unused. The central sector has the second-highest vacancy rate at 16 percent.

“There’s an interesting split right now amongst tenants. Some view their real estate as an extension of their recruiting efforts—wanting top notch space in premium locations,” said Mark Greiner, CWOC co-founder and partner, in a statement. “Others are trying hard to maximize the bang for their buck. An offshoot of Austin’s growth is that there’s a complete spectrum of opportunity.”