Total North American Hardware:
PS2: 44,470,146
XBox: 15,933,095
Gamecube: 12,695,401
XBox 360: 6,567,179
Wii: 3,841,070
PS3: 1,692,699
Percentage of Total North American Hardware:
PS2: 52%
XBox: 17%
Gamecube: 15%
XBox 360: 8%
Wii: 5%
PS3: 2%
So, (for the most part) the numbers are proportionate to the number of systems sold ...