CD audio books don't often make Amazon's top 100, let alone its top 20. But on May 21, the #15 title was the audio CD version of The 7 Habits of Highly Effective People. The audio book, released last month, jumped to #15 from #916,784, making it the greatest sales increase of the day by a huge margin. The paperback continues to sell well, and is ranked #81 on the bestseller list.