Renters are snagging newly constructed units at a record pace according to Zillow economist Aaron Terrazas. Based on data from the Census Bureau’s Survey of Market Absorption of New Multifamily Units (SOMA), almost 100,000 new apartments came online nationwide in Q3 2015, and a majority of them were rented within 12 months. That's 21% more apartments than a year earlier, 73% more than two years earlier, and is the most at any point since the late 1980s.
Even in the flood of new supply, more than 80% of these new apartments are rented within a year, with only 18.7% remaining unrented in the third quarter of 2015. More than half of apartments completed in any given quarter in the year rent within three months, and within six months more than 70% of newly constructed units are completed.
These ratios have been fairly constant over time, which is notable in the face of recent surges in newly delivered apartments – it suggests the recent building boom is roughly meeting demand, and neither exceeding it (which would cause absorption to fall) nor failing to meet it (causing a spike in absorption).