PHOENIX—Collier's fourth quarter office numbers are in and GlobeSt.com spoke with executive vice presidents of Colliers International in Greater Phoenix Keith Lambeth and Todd Noel to find out just what those numbers mean for the Valley.

GlobeSt.com: Vacancy in the Greater Phoenix office market continued to trend lower, ending the year at 17.8%. This marks the fifth consecutive year where vacancy has improved. Why do you think vacancy is trending lower in the office market this year and for five consecutive years?

Lambeth and Noel: Office vacancy is trending lower because tenant demand—fueled by office-using employment—is on the rise. It is no coincidence that the office vacancy rate began to dip in the first year that office-using employment started to expand again (2010). The pace of growth in these office-using sectors has picked up in recent years, particularly in the financial and professional segments of the economy, which have been expanding at a pace of 4% to 5% per year.