GameCube Vs. Wii U (Month To Month In NA)

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There's also this chart which compares Wii U/GCN/Dreamcast:

And this one which compares N64/GCN/Wii U:

I'm thinking somewhere between 250k (4.25x-ish bump) to 350k (6x over October) for Wii U in November 2013. Those are fairly generous Oct-November bumps. 

For example the 3DS went from 250k (October 2011) to 795k (November 2011; Mario 3D Land) to 1.1m (Dec 2011 approx; Mario Kart 7), so roughly a 3.15x increase from October to November. 

I think this puts into perspective though that the Wii U has a tremendous uphill climb just to match GameCube and N64 sales.