If Gran Turismo released every 2 years how much would each sell?

[Jaywood2010]

Troll_Whisperer said:
GT5 will easily sell surpass 10m, it may be there already since those shipment figures are old.

About the 2 year thing, dunno, it's hard to tell, maybe 8m each?

When was the last shipment?  IT was 9.2m or something right? Its been a while since ive heard