94%. Who and whom always turned my brain inside out, and it seemed as relevant as inkwells to me while growing up. I had also always assumed that e.g. and i.e. were essentially the same thing, so I learned something.

Now, given the poll results thus far, I am going to assume there is a lot of selection bias going on for who takes the poll -- or a lot of people are VERY lazy when they write.
Reading the typical internet discussion thread, between spelling and just using the correct word (not a word with a vaguely similar sound and a COMPLETELY different meaning -- don't they correct anyone's English papers in K-12 anymore? Or do they even study formal English?) -- the typical person seems to belong a LOT lower in the scoring than the poll showed. And now it's showing up in a lot of supposed formal journalism in supposed "high quality" papers and magazines. The WSJ comes to mind, where the supposed "editors" can't use the proper words in a title, much less spell them. If a journalist doesn't need to be reasonably well versed in the language she writes in, who does?
It "feels" to me like the same issue as inability for cashiers to make change when the cash register breaks -- basic lack of meaningful K-12 education.
Then again, when over half of people don't believe in a solid science which has been refined for 150 years (i.e. evolution) -- perhaps I expect WAY too much from pre-college schooling.
Given the track record of the perma-doomer blogs, I wouldn't bet a fast crash doomer's money on their predictions.