Per Census.gov
here, these are the income limits by each quintile of 23,507.6 households in 2009:
Lowest: up to $20,453
Second: up to $38,550
Third: up to $61,801
Fourth:up to $100,000
Fifth: $100,000+.
That means 80 percent of the country, about 94,030 households, makes $100,000 per year or less.
We know from IRS data that earners reporting adjusted gross incomes of approximately $67,000 or less in 2008, totaling $2.8 trillion in AGI, represented 105 million tax returns out of 140 million total. They are the bottom 75 percent of tax returns in the country, a rough proxy for the first 4 of the 5 income quintiles.
Using back of the envelope estimates, perhaps another 7 million more tax returns represent the rest of the territory up to $100,000, and AGI of another $0.6 trillion, meaning that the first 4/5 of the country contributes AGI of about $3.4 trillion.
Roughly 28 million tax returns would then round out the top quintile, with AGI of approximately $5 trillion. It is certain that 14.4 million of these returns account for $3.9 trillion of AGI, the top 10 percent of earners.
Thus one can estimate that tax returns from the top quintile have something like 6 times the AGI per return compared with the returns of all the quintiles below them taken together.
About 80 percent of the earners have 40 percent of the income, while the top 20 percent of the earners have 60 percent of the income.
That's where the money is.