If you are interested, there's a five minute test here: http://testyourvocab.com/
No downloads or e-mails or other crud.
When you get to the results page, you can either click the link on that page or just use this url: http://testyourvocab.com/blog/2013-05-08-Native-speakers-in-greater-detail#newMainchartNative
to find out what percentile you are for your age for people who took the test (who are mostly geeks).
My score was 26,000 words, which puts me roughly in the 55th percentile for my age. I'm okay with that. (Sorry if this is stupid.)