I'd be really interested in the percentiles of the
non-native speakers. With an alarmingly low 10.700 words, there is not even a percentile for me... And I know that my fluency of English is at least above the median around here (edit: here = where I live).
This also shows how extremely time-consuming it is to learn a second language. I started in school, 10 years old, am moderately well educated (some college drop-out), and use English on a daily basis. I also watch most movies in English (very seldom for people in a German speaking country to do), read some English novels, and also most non-fiction books I have are in English. Internet use is nearly English only.
Still, I probably have the vocabulary of an average 12 year old native speaker. After 17 years of learning and using the language, and at least 10 years of that using it _daily_.
Ouch.