I remember back when the PS3 was released there were people claiming that the negative media attention it was getting for failing to live up to the PS2 was undeserved because it was keeping pace with the sales that the PS2 had at launch. In hindsight we can all laugh at the people that thought it would continue to even hope to match the PS2's sales but here are the numbers for anyone interested in the widening gap between the PS2 and its successor.
(I put the thoughts at the time of some fanboys in brackets)
Year 1: PS2: ~7.026 million PS3: ~5.636 million Gap: ~1.39 million (Hardly the disaster for Sony people are claiming, right?)
Year 2: PS2: ~24.480 million PS3:~15.759 million Gap: ~8.72 million (Hmm. PS3/360 gap was not too far from that and PS3 is closing it)
Year 3: PS2: ~45.989 million PS3:~26.068 million Gap: ~19.921 million (Oh dear... lets stop comparing PS2 to PS3 and compare PS2 to Xbox 360 instead)
Anyways it will be interesting to revisit this thread in the years to come and see if the PS3 can manage to close some of that gap..