I doubt most people under the age of 20 know these characters in Europe.
Peanuts never got the constant repeats and remakes many 60s era cartoons received in a lot of Europe. In the UK, Peanuts have been pretty much absent except for references in American shows and movies. The last time I remember the characters doing something was for some McDonalds toys over a decade ago.
A good measure of popularity would also be merchandise. Toys R Us USA have 71 Snoopy toys, Toys R Us UK have 0.
In a statement about the new Peanuts show (being produced in France), a spokesperson for Peanuts even said "Peanuts is well-known in France to a slightly older age group".