My understanding is that majority of non-raw exports are in shipping containers and those have to be shipped back. So I would expect counts of loaded and offloa

My understanding is that majority of non-raw exports are in shipping containers and those have to be shipped back. So I would expect counts of loaded and offloaded shipping containers to be roughly similar. Interestingly, there are some synergies there - if a truck / train brought a shipping container to the port it's more efficient to put one, potentially empty, back for transport compared to running an empty train / truck. Notably I am assuming that shipping containers survive a large number of trips and their total number is not growing fast.