Although it's not saying that 51% are electric -- it's only saying that 49% are gasoline only. The 51% includes hybrid, plug-in hybrid, diesel as well as pure electric.

Hybrid vehicles are gas cars.

Let's use a cakes example. You can have all the chocolate you want in your cake, it won't be labelled as a chocolate cake but a poop cake as soon as you add poop to the recipe.