http://www.nintendo.co.jp/ir/en/library/events/151029/02.html
Well, let's compare Nintendo numbers (sell-through) with VGC numbers:
EUR VGC Wii U 4th Jan 2014 (1081778) until 20th Sept 2014 (1600257) = 518479
USA VGC Wii U 4th Jan 2014 (2138785) until 20th Sept 2014 (2812581) = 673796
EUR VGC Wii U 3rd Jan 2015 (2095567) until 19th Sept 2015 (2444711) = 349144
USA VGC Wii U 3rd Jan 2015 (3791344) until 19th Sept 2015 (4353269) = 561925
2014 until week 38 based on graphs:
EUR: around 450000
US: around 600000
2015 until week 38 based on graphs:
EUR: a little over 400000
USA: a little over 500000
So, USA and EUR are both overtracked by around 70K in 2014.
EUR in 2015 is undertracked by around 50K and USA is overtracked by around 50K.
VGC suggests that it's down globally YoY by over 250K, but it's probably just a little over 100K (Japan is up).
