Wii has moved under 200,000 a few weeks this year, but rebounded with stronger than normal weeks after. Generally speaking it seems that months with few Nintendo releases coincide with low Wii sales.
January had Warioware/Fire Emblem/Wii Play (USA/Jap/Others)
February had Wii Play (US)
March had .... (nothing? I need to check on this)
April had Super Paper Mario (USA/Japan)
May had Mario Party 8 (USA) Strikers (Europe...I think that is when it came out)
June had Big Brain Academy/Pokemon Battle Revolution (USA)
July had Mario Strikers (USA), Mario Party 8 (Japan I think)
August had Metroid Prime 3 (USA)
September has Super Paper Mario (Eur)/Strikers (Japan)
October has Batallion Wars (USA)
November has Galaxy (USA/Japan/Others) and maybe Brawl for Japan, and Prime 3 for Others
December has Brawl (USA), Wii Fit (Japan)
Obviously September should be down a bit until Strikers releases in Japan, and once the Metroid boost wears down a bit I imagine Wii will be back in the 85k range in the Americas until October.
People are difficult to govern because they have too much knowledge.
When there are more laws, there are more criminals.
- Lao Tzu







