[Question_Assumptions]

If the writer means the standard truckbound 20 or 40 footers, I highly doubt this number

It's plausible. During a storm, a whole column of them can peel off the side of a ship. A man who worked with me years ago had a wife who worked in shipping for a consumer electronics company and this was apparently a big enough concern for her that she'd always schedule her containers to arrive first and leave last so that they'd be stacked near the middle of the ship. I can't imagine her going through all that trouble if this didn't happen very often. There is also no telling how many containers get "lost" somewhere closer to the docks.

[ErnBatavia]

Anything's possible, but in 25 years of importing containers of seafood into the U.S. we heard of only one instance where a handful of containers got washed off in some typhoon.