I mentioned elsewhere that some stuff is lost in translation here: In Norwegian we don't say "I'm on the first floor", we either say "I'm in the first storey" or "I'm on the ground-level". For subsequent floors we use "I'm in X storey". I don't know how this works in other languages, but it would be strange if Norwegian was the only language where we use the storey to specify where something is, rather than the floor (i.e. using "in" rather than "on").

Well Sweden is wrong already :-)