Official Big 3 Quarterly/Annual Results for shipments to date & projections

[Skoom]

TheSource said:

September 2010 Shipment LTDS (to be updated)

System:  HW Shipped LTD / SW Shipped LTD

PS2: 147.6m / about 1521m (10.3 games per PS2 user)

DS: 135.58m / 773.34m (5.70 games per DS user)

Wii: 75.9m / 610.04m (8.04 games per Wii user)

PSP: 64.2m / 271m (4.22 games per PSP user)

X360: 44.5m / ??

PS3: 41.62m / 350.6m (8.42 games per PS3 user)

why is the sales on VGChartz for PS3 40.9 while 360 sales are at 44.7?