I read it decades ago in a book, can't recall which one. Anyhow, some googling came up with this: http://www.balancedreading.com/vocabulary.html http://www.bal

I read it decades ago in a book, can't recall which one. Anyhow, some googling came up with this: http://www.balancedreading.com/vocabulary.html http://www.balancedreading.com/vocabulary.html Specific counts vary widely, as it is hard to measure such things, and what counts as a word is also slippery. But the trend is pretty clear.