NEW HAVEN — For the third quarter in a row, greater New Haven reported the lowest apartment vacancy rate among 79 metropolitan areas tracked by the real-estate research firm Reis Inc. At the end of calendar 2013, New Haven’s apartment vacancy rate stood at 2.2 percent, down 0.4 percent from 12 months earlier. For the same period, average apartment rent in the market rose 2.5 percent, to $1,154.

For the same three-month period, the average apartment  vacancy rate nationwide was 4.1 percent, according to Reis. The U.S. average rent during the same period was $1,083, an increase of 0.8 percent.