How often do you buy new gaming hardware?

[Acevil]

PS2 (3 years)
Gamecube (Launch)
Wii (6 months after launch)
Xbox360 (2 years)
PS4 (1 year and 6 months I believe)
DS (I honestly don't know when, much later after DSlite)
PSP (Sometime before PSP3000 or at PSP3000)

3DS (Launch)
WiiU (Launch)
PS4 (Launch)
Vita (Five months ago)