1% of the US population are truck drivers[1]. 13% of an average american's income is spent on transport [2].

I'm going to assert that 100% of the income of that 1% of the population is less than 13% of the whole population's income.

[1]: http://www.alltrucking.com/faq/truck-drivers-in-the-usa/ [2]: http://www.bls.gov/news.release/cesan.nr0.htm