Wii U Vs. Wii Global:

Gap change in latest month: 2,127,336 - Wii
Gap change over last 12 months: n/a - Wii
Total Lead: 8,964732 – Wii
Wii U Total Sales: 3,461,900
Wii Total Sales: 12,426,632

The Wii U has been on the market for 10 months, but has never sold more than the Wii and has dropped further behind every month. However, first month sales were pretty similar with the Wii U only selling 57,559 units less than the Wii.

In the latest month the Wii U fell a further 2.13 million units behind the Wii, bringing the total gap to 8.96 million units. Both consoles launched in November, the Wii in November 2006 and the Wii in November 2012.

Source

Screaming.