I spent some time in the EU for work a few occupations ago. I don't know all the elements of corruption that composite those scores, but back in my day the two most corrupt European countries were (are?) Bulgaria and Romania. Because they lacked anti-bribery, anti-money laundering, and foreign corrupt practices laws, they were outside the EU Shenghen zone. For those unfamiliar, the EU isn't really the happy club we're led to believe. There are the cool-kid countries, where your EU passport lets you roll right across boarders free as a bird from France to Germany, for example. Then there are the shady characters like Romania and Bulgaria that are the stepchildren with fewer rights and privileges due to their unscrupulous behaviors.
How bad was the corruption there? Pretty bad. I was never allowed to delve deep into the risks and fraud potentials of my operations there and the local management team was always able to get the CEO to support their assertion I go F' myself and stop nosing around. (nosing around was of course my job)
Anecdotally, EVERY and I do mean EVERY advertisement at the airports was for goods and services to prevent bribery, scams, graft, phishing, cybersecurity, kickbacks, etc, etc. Totally corrupt shitholes per the definition used by President Trump. Ironically, very beautiful places to visit that didn't give off that Soviet-Satellite vibe you'd expect from Eastern Europe. The people were pleasant, but very distrustful and not very gregarious due to a lot of years of Soviet influence. They were the polar opposite of my work in Central America that is equally corrupt, but the people are so damned affable and humorous you just want to like them, even if they are robbing the company.