Win a Copy of the National Geographic Answer Book!

Every day, more than 20,000 Chinese people leave the countryside to settle in urban areas.
Related Link: For the past two weeks, we've been pulling Numbers of the Day from the beautiful and fascinating National Geographic Answer Book, which hit stores last Tuesday. You can order your copy from the National Geographic Store.
Want to Win a Copy? Leave a comment with an amazing demographic fact. We'll pick our favorite on Monday and award that person the book!
[See previous Numbers of the Day here.]