I got a 61%. Still high for a native speaker, it says.

I am not a native speaker, though.

One thing that's weird. It says: You said yes to 0% of the nonwords.

That sounds good. Apparently I never claimed to know a word that doesn't exist. But when I click on the "Nonwords you responded YES to" link, there is a word there. "Seconds".

Again, I am not a native speaker but I do believe that "Seconds" is indeed a word...