AHS Tariff: EU27 vs European Union -- How to reconcile for countries that joined EU after 2004?

[jvilag...@gmail.com]

I am downloading AHS tariff data for commodity HS8703 for each of the EU27 members and their partners from 2002-2012.

I see two options: European Union grouping and EU27 group. While I understand that EU27 wouldn't have had the 27 members back in 2002-2003, I am getting very different tariff rates depending on whether I select European Union or EU27 as reporter.

For example, if I want to see the tariff rates that the European Union imposed on Bulgaria back in 2002-2003 (before joining EU), why do I get different data if in essence the countries in the European Union or EU27 should have been the same in 2002-2003?

What group do I select to get the proper tariff data reflecting pre-post EU entry?

Thanks,