"The last figure I heard is that we use 13% of the world's oil. "
Your figure isn't accurate.
In 2004, domestic production of 5.4M barrels/day was 13% of the world's total production.
But our consumption is more than 25% of the world's oil and about 45% of the world's gasoline - and we harbor just 5% of the world's population.
http://www.gravmag.com/oilessay.html
Thanks. I stand corrected. It was a figure I heard on the radio the other night, and truthfully, it sounded a bit weak to me when I heard it.