It's amazing how differently sales numbers are handled in the U.S. and Japan. In Japan, we have weekly sales numbers for all platforms being published free to the public by Famitsu and Media Create. No fuss, no muss. In America, sales numbers are at least in principle closely-guarded secrets, with the NPD being the sentinels to keep the public from knowing how much each system sold each week. You can get that data if you want... for a price. Since 2011 pretty much everything we got has been through leaks. It's also nearly impossible to find older NPD data; they've been tracking monthly hardware sales since 1988, but there's nothing readily and publicly available online before 2000. I have been able to obtain yearly data from 1993 to 1999, however, but it wasn't easy.