Not surprised at the Nordic love of crime -- it long ago joined Japan and France as one of the main providers of non-English crime fiction.

I definitely have trouble buying that the US's top reads are classics. Romance, YA, or popular fiction (like Lessons in Chemistry). Searching doesn't imply reading, and I'd bet a lot of searches are by teens searching for book summaries and essay help.

Probably not, because genres themselves have so many layers, and genres differ by countries as well (Nordic Noir is different from the Japanese locked-room or organized crime works, etc). And the bigger issues are things like how many people are reading, period, and how varied their reading is, and other things that are probably a lot harder to measure.