Statistics Sweden (SCB, Statistiska Centralbyrån = The Central Bureau of Statistics) publishes some statistics on names in Sweden at http://www.scb.se/templates/Product____30895.asp
It's in Swedish, but here's a small glossary/explanation:
Efterfrågade tabeller och diagram = requested tables and diagrams
nyfödda = newborn
flicknamn = girls' names
pojknamn = boys' names
The yearly stats tables' header says "The table shows the 100 most common used first names given to boys/girls in YYYY. The names are displayed with the most common spelling, but all spellings are included in the count."
namn = name
antal bärare = number of carriers
Förändringar = changes (these are table showing trends)
Alfabetisk översikt = alphabetical overview
Header of the overview: "The table shows in alphabetical order all used first names given to more than ten boys/girls under any of the years 1998-2007. Every spelling is shown as a name of its own. - = fewer than 10."
Topp 100 listor, Hela befolkningen = Top 100 lists, whole population
därav som tilltalsnamn = of which as used first name
andel tilltalsnamn (procent) = fraction used first name (per cent)
A little note: A Swedish name is stipulated by law to consist of one or more first names, an optional (and rare) middle name (in the Danish sense, so it could e.g. be the name of a farm), and a surname. This is contrary to how the term "middle name" is commonly used even in Swedish, but part of the reason for the confusion could be that it's common to go by a different first name than the first by order. That is, someone named "Sven Gunnar Nilsson" might go by "Gunnar", and this would be known by the authorities and reflected in the statistics (as the "used first name" above).