It's pretty minor.
Wii jumped from 400k to 700k in Feb 08 to March 08 with Smash, and then stayed at 700k+ a month. Then from March to April Wii went from over 700k in five weeks (over 140k / week) to over 700k in four weeks (over 175k / week).
Wii U went from 15k / week in May to 28k / week in June. The Mario Kart boost is essentially 40% of what it was on Wii.
People are difficult to govern because they have too much knowledge.
When there are more laws, there are more criminals.
- Lao Tzu