It is not counted as such but it is very much tied to it and for the most part goes up and down with the Euro economy barring some own goals.

While similar to Denmark and Sweden it retained its own currency, and was also not part of Schengen, It was part of the Single Market.

Sweden does not have an opt out for the euro.

Sweden just haven’t completed the stabilization and alignment criteria to formally switch over, arguing that it is voluntary.

We had a referendum on the euro back 2003 with a clear mandate to not adopt it and the politicians don’t want to poke the sleeping tiger that is the euro question.