From the Journal of Commerce:

Shippers can expect more cargo to be “rolled” to later voyages as container lines continue to cut costs by slow-steaming and laying up vessels, Drewry Maritime Research said in its latest Container Insight Weekly.

Drewry said slow-steaming and layups allowed carriers to limit effective capacity growth to 22 percent since 2008, despite introduction of larger ships. Without those measures, capacity would have grown 40 percent, Drewry said.

“In 2013 alone, slow-steaming and layups reduced available supply by nearly 3 million TEUs,” Drewry said.

More at the JOC