Which country in the European Union has the lowest gross and per-capita research output (both academic and industry)?
Why is that?
There's a nice, sortable table for R&D spending on Wikipedia. The EU country spending the least on a per capita basis is Romania (albeit with 2016 data). It's not exactly R&D output (how would you measure that?) but low spending correlates strongly with low output.
Wikipedia also gives reasons for this: corruption, low funding, and a considerable brain drain. This is the source cited. It is 20 years old at this point, but given funding remains low, it's probably still applicable to some extent.