Truckers ended 2015 on a high note, increasing tonnage about 1 percent in December compared to the same month a year earlier.

But 2015 was still tough for the industry.

“Tonnage ended 2015 on a strong note, but it was not strong for the year as a whole,” said Bob Costello, economist for the American Trucking Associations. “With year-over-year gains averaging just 1.2 percent over the last four months, there was a clear deceleration in truck tonnage.”

Tonnage was up 2.6 percent for all of 2015.

The trade group’s seasonally adjusted For-Hire Truck Tonnage Index increased 1 percent in December, following a decrease of 0.9 percent during November. In December, the index equaled 135.6, up from 134.3 in November. It stands just below the all-time high of 135.8 reached in January 2015.

Costello said he remains concerned about a high level of inventories throughout the supply chain.

“The total business inventory-to-sales record is at the highest level in over a decade, excluding the Great Recession period. This will have a negative impact on truck freight volumes over the next few months at least. And, this inventory cycle is overriding any strength from consumer spending and housing at the moment,” he said.

Motor carriers annually collect about $700 billion, or 80 percent, of total revenue earned by all transport modes and are an important economic barometer.