The Multifamily Production Index (MPI), released last week by the National Association of Home Builders (NAHB), fell slightly in the second quarter of 2016, dropping three points to 50. This is the 18th consecutive reading of 50 or above.

The MPI measures builder and developer sentiment about current conditions in the apartment and condominium market on a scale of 0 to 100. The index and all of its components are scaled so that a number above 50 indicates that more respondents report conditions are improving than report conditions are getting worse.

The MPI provides a composite measure of three key elements of the multifamily housing market: construction of low-rent units, market-rate rental units and “for-sale” units, or condominiums. The component measuring low-rent units decreased two points to 52 in the second quarter, while market-rate rental units dropped five points to a level of 53 and for-sale units fell three points to 45.

The Multifamily Vacancy Index (MVI), which measures the multifamily housing industry’s perception of vacancies, increased three points to a level of 42, with higher numbers indicating more vacancies. After peaking at 70 in the second quarter of 2009, the MVI improved consistently through 2010 and has been fairly stable since 2011.

“Despite the modest decline this quarter, multifamily developers are still reporting steady demand,” says Andrew Chaban, CEO of Princeton Properties in Lowell, Mass., and chairperson of NAHB’s Multifamily Council. “While conditions certainly vary market by market, we are optimistic that the apartment market will remain strong for the year.”

“The slight drop in this quarter’s Multifamily Production Index is consistent with the NAHB forecast of a leveling off of multifamily production after multiple years of strong growth rates,” says NAHB chief economist Robert Dietz. “Nonetheless, we expect multifamily development to remain at above normal levels as demographics remain favorable and the market seeks a balance between supply and demand.”

Historically, the MPI and MVI have performed well as leading indicators of U.S. Census figures for multifamily starts and vacancy rates, providing information on likely movement in the Census figures one to three quarters in advance.