As seen on blog.800ceoread.com:

We move a whole lot of business books around the world from our humble offices here in Milwaukee, Wisconsin. Each and every month, we compile our sales numbers and release a bestseller list to recognize the books that are heading out to business people, business schools, and entrepreneurs to help spread ideas, solve problems, promote change, and inspire leadership in the business community. We’ve now compiled those numbers for the entire year, giving weight to both total sales numbers and how long each book stayed on the list (and at what number) and are happy to announce the bestsellers of 2012.