How close was my 2001 prediction about cars?

Back in '01, I collected a bunch of predictions about 20 years in the future (so, next year).  I figured 20 years was a large enough time span to be interesting, but short enough that I'd actually remember I'd done it.

One of the predictions I made was that around half of the cars on the road would be powered by something other than gasoline-powered standard internal combustion engines (hybrids, electric, natural gas, fuel cell, whatever, I didn't specify what other than not standard gas-powered ICEs)

Anyone have any numbers on how close to accurate my prediction is, at this point, for either the US or the world as a whole?  (we're not quite to 2021 yet, but I figure the composition of cars on the road won't change *that* much in the next 6 months or so)