Thank you for your reply.

Then, I have two further questions on this:

1. Why this "imports-from-a country itself" only happens after around 2001? You may check the data, there is no such problem for early years.

2. I've noticed that your export data acturally includes "re-exports" as well, why there is no such problem for exports at all? (means there is no "export-to a country itself" at all in your database, for any product, any country, any year.)

 Thank you very much! Your help is really appreciated!

Best,

Anne