Developers will begin construction of 405,000 multifamily units in 2015. That’s according to the new analyst report from Dodge Construction Outlook. A post on the National Real Estate Investor website says people in their early 20s are fueling the market. The post compares data from 2012 to present, and looks ahead, too. There’s a strong demand for multifamily housing of more than 400,000 units a year from 2015 to 2017, compared to the average of just 296,000 apartments completed annually from 2012 to 2014, according to data firm RCLCO, a real estate advisory firm.