Well, your numbers aren't totally correct, as you're comparing different time frames.
I'll do it another way.
Xbox original
2001: 1.7M (not a full year)
2002: 5.7M
2003: 5.8M
2004: 7.0M
2005: 3.8M
2006: 750K
Xbox 360.
2005: 1.3M (not a full year)
2006: 6.9M
2007: 8.1M (first half sales: 2.5M
2008 first half: 3.76M
What you see here, is that in 2006, the 360 sold 21% more than the original's 2002 sales. In 2007, the 360 increased by about 13%, and sold 40% more than the original did in 2002.
In 2008, the 360 is tracking to sell 40-50% more than it did in 2007, meaning that it should sell 10-12M. This would mean that the 360's 2008 will sell around 50% more than the XB did in its peak year.
In 2009, the 360 could very well see a 100% increase over the original's 2005.
http://www.vgchartz.com/games/userreviewdisp.php?id=261
That is VGChartz LONGEST review. And it's NOT Cute Kitten DS







