Smaller markets are leading apartment rent growth metrics across the country.

Twenty-two of the nation's 150 core apartment markets recorded rent growth of more than 3.5% year over year at the end of May, all of which were secondary or tertiary markets. That compares with the overall U.S. average annual rent increase of just 0.2% in May, according to data from RealPage Market Analytics.

New York markets represented three of the top 10 growth performances over the past year with rent growth of between 5% and 7% in Syracuse, Buffalo and Rochester. All three markets, which are situated along Interstate 90 in the northwest portion of the state, also ranked in the top 25 for occupancy among the 150 core apartment markets in May, RealPage said.