Test Your Vocab is part of an American-Brazilian research project “to measure vocabulary sizes according to age and education, and particularly to compare native learning rates with foreign language classroom learning rates.” (The Brazilian project hasn’t launched yet.) The first part of the test determines general vocabulary level; the second part has “a larger but narrower selection of words to determine the vocabulary level with greater precision.”I missed mawkish, pastiche, chivvy, adumbrate, disjunctive, melange, sedulous, epigone, captious, tenebrous, embonpoint, pother, valetudinarian, cenacle, cantle, clerisy, deracinate, fuliginous, oneiromancy, caitliff, funambulist, and opsimath. That's 22 words (which a certain blogger will find interesting). The test seems to measure only knowledge of conventional words, not the specialized vocabulary of science specialties, etc., and doesn't calculate your knowledge of non-English words. Feel free to brag about your results in the Comments.
The test is here. At the test's blog they provide this graph of vocabulary acquisition vs. age: