According to Nintendo of Europe's internal sales panel NDS has become the best ever selling video game system in Europe with 40M units sold, they also claim Wii to be "the fastest selling home console in Europe by reaching the 20 million milestone in just over three years". Whilst they didn't give out annual sales, they previously gave out annual and LTD sales for 2008, making it possible to calculate 2009 sales.
2009 European Sales (2008) [LTD]:
NDS: 9M (11.2M) [40M]
Wii: 5.8M (8.3M) [20M]
That puts Wii down 30% and NDS down 20% during 2009.