This article in the New York Times talks about the difference in sales between genre fiction and literary fiction. As its example, Gilead by Marilynne Robinson has sold 345,000 copies, which is impressive unless it's compared to The Da Vinci Code's 60 million. Of course, not all genre fiction is equal; this article at The Book Standard gives Terry Brooks a pat on the back for selling 72,000 copies of his last fantasy novel Straken: High Druid of Shannara, Book 3. And Brooks is considered a big name in Fantasy.
There's a dramatic difference in scale between books and other media—especially the big three, television, movies and video games. (The Internet is sometimes mentioned alongside those three, but this is a mistake. The Internet is not a medium at all, but a delivery system for media—on the Internet one can watch movies and television, play video games, read books, as well as comic books, poetry, etc.) If a book sells 100,000 copies it is a huge bestseller. If a television show has 100,000 viewers, it is cancelled. Of course, the 60 million copies of the Da Vinci code is impressive any way you look at it. A movie that sold 60 million tickets at $10 a pop would have grossed $600 million dollars, which about matches the total take of Titanic in the United States, the biggest box office hit of all time. (Of course, the 60 million represents Da Vinci's worldwide numbers, but still.)
It's little wonder that there are so many products nipping at Da Vinci's heels, so that Barnes and Nobles these days looks more like Da Vinci Code Land. The Da Vinci Code is the classic blockbuster, the book that dwarfs all other books by comparison and makes all book executives drool. What is the secret of its success? The four -page chapters maybe? Who the hell knows. But one thing The Da Vinci Code does demonstrate, and it's something that I haven't seen anyone else point out, is that there are enough people out there willing to read a book to sell 60 million copies of this one thing. There must be a way to get more than one title into these people's hands, other than the Oprah Book Club.