Does anyone have any statistics on how long "Getting Things Done" has been on the best sellers list or any way to find this information out easily?

From DA's recent blog entry (http://www.davidco.com/blogs/david/a..._the_rise.html)
"GTD made #1 in this month's Business Week bestseller list, as well as making it to the NY times bestseller list of advice paperbacks."
I looked out at the NY Times and the Business Week sites, but couldn't find the information easily.

Thanks in advance for any help in finding this information.

Regards,
Kurt