Using the weekly historical data here on VG chartz, at 30 weeks into the PS1 lifespan (June 25, 1995), it had the following numbers:
cumulative hardware: 962,377
cumulative software: 3,896,557
This results in a cumulative attach rate of 4.05
The weekly Wii data for June 24, 2007 shows:
cumulative hardware: 2,838,463
cumulative software: 6,644,098
This results in a cumulative attach rate of 2.34
Obviously the PS1 is higher as others in this thread have guessed. I'm too busy to do it right now, but now I'm curious to see how all the other consoles have done at the 30 week mark. Hopefully I can do that tonight.
And though this should be obvious to anyone paying attention to the thread, I'll state it anyway. This is Japanese data, not worldwide or US or anything else.








