One reason that new construction hasn't kept pace with demand is that deliveries over the past year came in at a slower pace than expected, pointed out Greg Willett, VP research and analysis at MPF Research. The year was supposed to see a 20% increase in deliveries compared to 2014; instead, '15 came in 8% lower.

Earlier this week, in a report from MPF, the rental market intelligence division of RealPage, Willett explained the shortfall. He said that delays in deliveries, due in large measure to labor shortages in select building trades, have had a significant impact on the apartment market's overall performance.

"Pushing back completion dates two or three months is translating to a longer pre-leasing period for new properties coming on stream," said Willett. "Those new projects are finally opening with better-than-expected occupancy, and that occupancy premium helps boost rent growth."

And rent growth certainly was widespread last year, although during the Humphreys webinar Willett made it clear that it wasn't occurring at high levels across the board. Annual rent growth in the West was 6.8% in '15, aided considerably by a handful of West Coast cities with double-digit annual rent increases; across the continent, it was less than half that velocity at 3.2%. Among the 100 metro areas that MPF covers, rent growth was higher on average in the 50 largest metros than in the next 50.

Bibby posed questions that remain to be answered this year, to wit: "How long will this run go? What will millennials do about owning? Is the reinvestment in America's downtown a trend or passing fancy? What is the 'end game' for Fannie and Freddie? Are we running into capacity problems on college campuses? Have dropping oil prices helped or hurt multifamily, or has it been a wash? When will we see legislative action re: housing finance reform? Will we see more Congressional challenges of the authority of regulators, especially EPA and HUD? Will we see any form of comprehensive reform of anything (taxes, immigration, etc.)?"

To help industry players sort out of some of these questions, NMHC's 2016 Annual Meeting is coming up, Jan. 19-21 in Orlando, to be followed in February by RealShare Apartments East, scheduled for Feb. 23 and 24 in Miami. Click here for further information on RealShare Apartments East.