That's a no brainer. I said bigger percentage of income. Families who make less than $75,000 a year (well above the poverty line) spend a lot greater percentage of their income on sales taxable items than families who make over. You're talking about multiplying their sales tax by at least x5 for necessities while the rich beat the tax by cutting back on frivolous items thus negatively affecting the economy in the process.
I suggest you do more research at www.fairtax.org
I researched enough to see that Boortz is trying to sell a book to fools.