US not even in the top 10 of world democracies?

http://www.economist.com/markets/rankings/displaystory.cfm?story_id=8908438

1. Sweden
2. Iceland
3. Netherlands
4. Norway
5. Denmark
6. Finland
7. Luxembourg
8. Australia
9. Canada
10. Switzerland

So... where is the US? Number 17.
The details of how this list was created are important, but for an influencial paper to leave out the US even from the top 15 is very telling that something is wrong here.
http://www.economist.com/media/pdf/DEMOCRACY_INDEX_2007_v3.pdf shows their methodology.