The June 2015 national annual effective rent growth rate of 5.1 percent represented a 47-month high, and continued a streak of 5 percent-plus rent growth that is now the longest in at least six years.

Axiometrics called 2014 "The Year of the Apartment" because the apartment market showed such strength. The effective rent growth in June 2014 was 3.7 percent, putting June 2015's exceptional performance into perspective.

Though effective rent growth was also 5.1 percent in April and February, the June rate was the highest when extended to two decimal points (5.11 percent). This is the highest rate since the 5.3 percent of July 2011.

The metric has reached at least 5 percent for five straight months, the longest such streak since Axiometrics started monthly reporting of annual apartment data in April 2009.

The June national annual effective rent growth rate was 9 basis points (bps) higher than May's 5 percent and a 143-bps increase from the 3.7 percent of June 2014.

The average same-store rent was $1,234 per month in June, a $20 increase from May and $60 higher than in June 2014.

Five of the top seven rent-growth markets were in California, with Oakland No. 1, followed by Portland and Denver.

National year-to-date (YTD) effective rent growth reached 4.7 percent in June. This was the third month that 2015 monthly YTD rent growth rates outperformed all post-recession counterparts.

Occupancy rates stayed high nationally in June, remaining at 95.3 percent-though the latest rate was a 2-bps increase from May when extended to two decimal points (95.30 percent from 95.28 percent).

As the graph shows, occupancy rates typically peak during the middle of the year, then moderate as the year comes to a close. Considering the current strength of the apartment market, less of a decrease in occupancy could occur at the end of 2015.  —Axiometrics