This likely shatters records, but the NYT's doesn't care. The NYT's book review has banned childrens books form their best sellers list.
Asking around the office here, I suspect that there might be more adults reading the book than kids. And given the themes in the book, I think that while the series might have started for kids, it has matured.
Personly, I would like to see the book on the list in the place it earned and rightly deserves, #1.