Hrm... this is kinda tough. I'm just going to mention when a system came into prominence for my playing; this does not mean that I stopped playing the other systems. (Yes, I've used my NES some this year!) Any skipped years mean that my main system was not changed from the prior year(s).
1983: Atari 2600 (Yes, I started gaming that young. I remember being angry at a friend turning off the system because my game was going "too long"- defined as 15,000 points with 1 ghost in Jr. Pac Man.)
1987: NES
1990: Game Boy
1991: NES (again)
1992: SNES
1995: Game Boy, through the SNES adaptor. So which does that count as?
1996: SNES
1997: N64
1998: PS1 (Yeah, the 64 wasn't getting my RPGs; Quest 64 just didn't cut it.)
2002: GBA (I was about done with home consoles...)
2004: No dominent system. (I was losing interest in gaming by this point.)
2006: DS (This was my make-or-break system for gaming... you see where I am now...)
2008: PS2 (One word: Atlus. Though this would transfer...)
2009: DS (Yep, more Atlus. And this is by far my most used system for this year.)
Systems owned not mentioned: GBC, Gamecube, Wii, Genesis, Saturn, Dreamcast, PSP, XBox, 360, Atari XE, FDS. Though out of fairness, some of these were gotten late or post-cycle.
-dunno001
-On a quest for the truly perfect game; I don't think it exists...