I think Swedes were considered to have the best knowledge of English among non-native-English speakers. English is taught from early on in Sweden, at least these days. Typically, in Sweden, as long as there is one Enlish speaker in a group, the lectures, seminars, and private conversations all convert to Enlgish. This is not quite as true in Holland or Germany , etc. In the latter, one is more expected to learn Dutch, German, etc. But they are similar. France, on the other hand...
I agree that Swede's often are english fluent and knowledgable, but to my ear, I still say the Dutch have the accent that is most 'american.'
I think that part of the reason the smaller population countries have populations with a high number of english speakers, is that many of their textbooks (particularly in college) are in english as it is not economically worthwhile to translate low volume books into a language spoken by a small population.