The report, by real estate management firm Jones Lang LaSalle, found the biggest jump in vacancies has been along the Route 78 corridor.
The report also found the amount of office sublease space available totals a half-million square feet, with 21 percent vacant.
The report blames the rising vacancies on higher unemployment, companies trying to do more with less workers in a shaky economy, and recently finished construction projects that haven't been leased yet.
