Driver turnover for large fleets surpassed the 100% mark for the first time in more than four years, according to the American Trucking Assns. (ATA).

ATA’s quarterly Trucking Activity Report noted that linehaul fleets reporting more than $30 million in revenue saw a 16% rise in driver turnover in the second quarter, reaching 106%. The last time it was over 100% was the first quarter of 2008 and the current level is the highest It’s been since the fourth quarter of 2007.

“We continue to see steady, albeit sluggish, growth in freight volumes, which increases demand for drivers,” said Bob Costello, ATA chief economist. “That, coupled with continued pressure on fleets to improve their safety records as a result of regulatory oversight changes, is increasing competition among carriers for drivers with clean histories.”

The turnover rate at smaller truckload fleets also rose, climbing 15% in the second quarter to 86%. That is the highest point since the third quarter of 2007.

“We have been contending that the driver shortage is by and large qualitative, rather than quantitative,” Costello said. “Despite some estimates, I believe that in terms of raw numbers, the trucking industry is currently short somewhere in the range of 20,000 to 30,000 drivers. However, if we continue to see growth in freight volumes, we can expect that number to rise in the near future, exacerbating the qualitative shortage and creating a quantitative one.”

The turnover rate for less-than-truckload fleets averaged just 9% in the second quarter, up from 8% in the previous quarter.