why do scandinavians speak such good english?

Scandinavians seem to be particularly good at English.

Here are some entries from the AntiMoon blog:

The answer to your question: original or dubbed tv/movie products: 

1. Original voice in Tv products and movies is used in: 
Portugal, Flanders, Netherlands, Scandinavia, Slovenia, Croatia, Serbia, Bosnia 
2. Dubbing is preferred: in most other countries 

That's why people from 1. are more likely to speak English on the street with foreigners, and their English is better than English of Germans, French, Spanish or Italians, Italians have terrible diction: pub ['peb@], dance ['dens@], cover ['kover]...

Why do Dutch and Scandinavians speak English so well? | Antimoon Forum
Question for Scandinavians | Antimoon Forum

As mentioned above, all films in Germany are dubbed into German while the Dutch watch the original language versions and can also pick up English TV broadcasts. 

Why are Germans among the worst speakers of English? | Antimoon Forum

And from other blogs:

I am from Poland and we had a Swede paying a visit and telling about the English of Scandinavians. 
The reasons are: 
- they listen to a lot of English tv with native subtitles 

Why do Scandinavians speak such good English?

Because we learn it at school. Besides, we don't dub TV shows or films. The very idea strikes us as barbarous. Everybody can read subtitles

How can Scandinavians speak English so well?

And from professionals:
Why do Scandinavians speak such a high standard of English? - The Translation People - Blog
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