FYI.  There is a private company called Piers which tracks trade flows by ports by examining the vessel manifests and bills of lading.  They have a website which Luis Velez is familiar with and is www.piers.com.  While they don't track all regions of the world, they do provide data by port.  Unfortunately, this information requires payment.  I would suggest looking on their website to see what they have to offer.

KC