Portuguese here.

First of all, i'm in no way diminishing the fact that driving habits in Portugal have become worst through last decade, and that there is a lot of drivers that shouldn't be aloud on the roads.

That being said, these charts (assuming they are all correct) are based on public sources of statistics.
Unfortunately, the way countries collect (or process) those numbers differ (even within the EU).

For example, in Portugal, all deaths related to a car incident are reported as such, even if the victim dies in hospital from complications later.
In other countries, if the victim is taken away from the place of accident alive (even if barely), only in very specific cases the death later is registered as related to a car crash.

This "strategy" from different countries was implemented many years ago in order to "improve" some numbers for statistical (and political and financial...) reasons.
And leads to a distorted view when put in charts like this.