The turnover rate at large truckload carriers increased in the first quarter of 2018, reflecting how fleets are struggling to retain and recruit new drivers as freight demand rises.

The annualized turnover rate jumped by six points to 94% through the first four months of the year and is 20 percentage points higher than it was in the first quarter of 2017, according to American Trucking Associations’ Trucking Activity Report.

“The uptick in turnover is consistent with continued tightness in the market for drivers,” said Bob Costello, ATA chief economist. “Anecdotally, carriers continue to struggle both recruiting and retaining quality drivers – leading to increasing wages. The tight driver market should continue and will be a source of concern for carriers in the months ahead.”

For small carriers, turnover fell to 73% but that was still seven points higher than the same time period last year. The turnover rate at less-than-truckload carriers also increased two points to 10%.

“Turnover is not a measure of the driver shortage, but rather of demand for drivers,” Costello said. “We know that as freight demand continues to rise, demand for drivers to move those goods will also rise, which often results in more driver churn or turnover. Finding enough qualified drivers remains a tremendous challenge for the trucking industry and one that if not solved will threaten the entire supply chain.”

Related: Younger Truck Drivers Slightly More Prone to Turnover