Mike B, we have no idea which countries ioi includes in Others or which in Other Europe, or in fact which countries might be included in with larger neighboring countries (the American charts definately include Canada and Mexico...and possibly the South American countrys)
It's probable that all three systems are undertracked due to lack of info for some countries, PS2 is probably undertracked worldwide by a million or two just because ioi will be focusing on places where current gen is available even though last gens PS2 will be available in more countries.