The turnover rate at large truckload carriers fell six percentage points to 91% in the fourth quarter of 2013, but held above 90% for the eighth consecutive quarter, according to new figures released by the American Trucking Associations.

The decline was the second straight for the measure of churn in the driver pool, however, ATA Chief Economist Bob Costello said it continues to be elevated.

“We saw turnover at fleets with at least $30 million in annual revenue bottom out near 50% at the depths of the Great Recession and have increased steadily since,” he said. “The rate appears to have flattened out at an elevated level for the moment. However, it could easily increase as tightness in the labor pool should continue, and even worsen, as the economy improves.”

For all of 2013, driver turnover averaged 96%, just below 2012’s average of 98% and well off the all-time high of 130% set in 2005.

Turnover at small truckload fleets rose five points in the final quarter of the year to 79%, but was still below the 82% mark the figure hit in the first half of 2012. For the year, turnover at small fleets averaged 82%.

Turnover in the less-than-truckload sector fell two points to 11% in the fourth quarter, which was also the average for 2013.

Looking ahead, Costello said he expects stronger economic growth and increased growth for the trucking industry, which in turn will put more pressure on the driver market and the driver shortage.

“At the moment, we already have 30,000 unfilled jobs for drivers in the trucking industry,” he said. “As the industry starts to haul more because demand goes up, we’ll need to add more drivers, nearly 100,000 annually over the next decade, in order to keep pace.”