The PS3 sold a ton of units everywhere on its first week but after initial demand was satisfied the number of units sold dropped dramatically. Now suppose sales per week went like the following
25,000 + 10,000 + 5,000 + 2,000 + 1,000 + 1,000 + 1,000 + 1,000 + 1,000 + 1,000 + 1,000 + 1,000 = 50,000
And over the same timeframe the Wii has been selling like this
4,000 + 4,000 + 4,000 + 4,000 + 4,000 + 4,000 + 4,000 + 4,000 + 4,000 + 4,000 + 4,000 + 4,000 = 48,000
Certainly, in the time since the PS3 has been released it has outsold the XBox 360 and Wii but it is likely that this will change in the very near future.







