First, if the numbers were any good, Google would be bragging about them instead of hiding them. That shows how badly they're selling. Because of this, we have to use the numbers we can get. If you have any better metric, let me know.
Second, if you hadn't failed reading comprehension, it says right there in the summary that the 5000 figure is from 2011 from the first six months of selling them.
Also, the Nokia Windows Phones were bestsellers on Amazon, so you're arguing that they sold really well?