Sales are Sales.Scum & Villiany does okay, but it's not on the level of the first four on that list. I could be wrong, but I get the impression that Coriolis and Blue Planet are more "ooh, I love reading about this setting" rather than "I actually play this".
GURPS books are traditionally far more owned and read than played. Or used as sourcebooks for other systems.
OG Paranoia was FAR more owned than played back in the day. Not sure if that's changed.
