Big Brother knows what you don't know

Assuming the reason people look up a word in their Kindle dictionaries is because they don't know its meaning, Amazon knows what it's customers don't know. They recently released a list of the most-looked-up words. I knew a lot of them, but some (see yellow highlighting) were unknown.

The built-in dictionary is a great feature of ereaders, but it's kind of creepy to think Amazon is tracking which words are looked up.