Ahhh. Great! A capable person making a more interesting point.
I was just aiming for a rough and ready ballpark figure. There are a lot of authours not available in Perseus that I would have liked to have included too. I expect that as the corpus of texts included in this count grows, the number of words used once will go down.
I'm too close to the fire to see the flames on the difference between Koine and Attic vocabulary. I need to give that question some analytical and statistical distance.