There are twenty-eight national parks in Sweden; the latest one opened in the summer of 2002. Sweden was the first European country to create national parks. The first nine were officially declared open on May 24, 1909.
For the curious and those planning to visit, the Swedish word for national park is (lo and behold!) nationalpark (note: no "särskrivning"). The plural is nationalparker; the definite form is nationalparken and the definite plural is nationalparkerna.
Sweden's Right of Public Access law ("allemansrätten") increases the need to have protected areas in nature (despite its protective clauses), and in fact, 1.5% of the country is part of a national park. Another 6.5% of the country is a part of nature reserves and wildlife sanctuaries.
Applicable regulations differ from park to park, so do your homework before you go and set up a fireplace in one of them and end up burning down some ancient piece of forest (as happened with Tyresta, although that seems to have been rather deliberate). Thank you. (Note to fellow noders: please include the rules of any Swedish national parks that you node. All the info you need is available at www.environ.se provided by the Swedish Evironment Protection Agency.)
And these are the national parks of Sweden, with the years they were created. (Where several years are given, the park has been expanded after its initial creation.)