One key indicator has joined the swirling concerns about the state of the international economy now that the calendar has turned to 2019.

The manufacturing index from the U.S. Institute for Supply Management dropped more in the month of December than it has since 2008, Bloomberg reports. The index dropped 5.2 points to 54.1, a drop only surpassed at the outset of the Great Recession and in the month following the Sept. 11 attacks in 2001.

The ISM's index holds the number 50 as the divider between an expanding economy and a contracting one, and the current number is the lowest it has been since 2016, as the manufacturing industry raised itself out of a brief contraction period. Manufacturing in the U.S. may not be the crux of the industrial real estate market like it once was, but it still is a key bellwether for economic health, according to Bloomberg.

Federal Reserve Chairman Jerome Powell has indicated that interest rate hikes might be slowed in 2019 in response to slowing markets abroad, trade wars and the lack of runaway inflation, Bloomberg reports. The addition of manufacturing concerns led Dallas Federal Reserve Bank President Robert Kaplan to call for a freeze of rate hikes altogether, until at least one of those factors was resolved, Bloomberg reports.

Though the blossoming e-commerce market has kept distribution center demand healthy, growing federal interest rates are among the main reasons for what is expected to be a relatively flat year in certain sectors of commercial real estate. As the stimulus effect from the Tax Cuts and Jobs Act of late 2017 recedes and the national and global political climate remains tense, outlooks have been darker in the industry than in previous years.