Where Did the Harry Potter Readers Go?

Here is an interesting article. AbeBooks tracked Harry Potter readers to see what they read after the Potter books. Any guesses? Well, they went practically everywhere.
Top ten:

• 7 Habits of Highly Effective People - Covey
• Unbearable Lightness of Being - de Rossi
• The Bluest Eye - Morrison
• The Dukan Diet Recipe Book - Dukan
• The Postmistress - Blake
• Beloved - Morrison
• How to Stop Worrying and Start Living - Carnegie
• The Soloist - Lopez
• Cather in the Rye - Salinger
• Land of Painted Caves - Auel

What I'd be more interested in is some idea of whether they bought more or less books than the average reader.