When will low carbon new vehicle sales (e.g. electric, hydrogen, plug-in hybrid) be more than 90% of all new car sales in the USA?

For the purposes of this question a low carbon vehicle can be a plugin hybrid, a purely electric vehicle, a hydrogen powered vehicle, or any other that doesn't directly generate significant amounts of carbon emissions. The average vehicle generates 300-400 g CO2 per mile driven so any vehicle generating less than 40g CO2 per mile driven should qualify (with the caveat that combustion-engine vehicles running on gasoline that aren't plugin hybrids will never qualify).