What I posted before was their conclusions from the study as a whole. What you are doing above is cherry picking. Again, from their conclusions:
Here are some dramatic facts that sum up how the wealth distribution became even more concentrated between 1983 and 2004, in good part due to the tax cuts for the wealthy and the defeat of labor unions:
Of all the new financial wealth created by the American economy in that 21-year-period, fully 42% of it went to the top 1%. A whopping 94% went to the top 20%, which of course means that the bottom 80% received only 6% of all the new financial wealth generated in the United States during the '80s, '90s, and early 2000s (Wolff, 2007)."
"And now we have arrived at the point I want to make. If the top 1% of households have 30-35% of the wealth, that's 30 to 35 times what we would expect by chance, and so we infer they must be powerful. And then we set out to see if the same set of households scores high on other power indicators (it does). Next we study how that power operates, which is what most articles on this site are about. Furthermore, if the top 20% have 84% of the wealth (and recall that 10% have 85% to 90% of the stocks, bonds, trust funds, and business equity), that means that the United States is a power pyramid. It's tough for the bottom 80% -- maybe even the bottom 90% -- to get organized and exercise much power."
"And the rate of increase is even higher for the very richest of the rich: the top 400 income earners in the United States. According to another analysis by Johnston (2010a), the average income of the top 400 tripled during the Clinton Administration and doubled during the first seven years of the Bush Administration. So by 2007, the top 400 averaged $344.8 million per person, up 31% from an average of $263.3 million just one year earlier. (For another recent revealing study by Johnston, read "Is Our Tax System Helping Us Create Wealth?").
How are these huge gains possible for the top 400? It's due to cuts in the tax rates on capital gains and dividends, which were down to a mere 15% in 2007 thanks to the tax cuts proposed by the Bush Administration and passed by Congress in 2003. Since almost 75% of the income for the top 400 comes from capital gains and dividends, it's not hard to see why tax cuts on income sources available to only a tiny percent of Americans mattered greatly for the high-earning few. Overall, the effective tax rate on high incomes fell by 7% during the Clinton presidency and 6% in the Bush era, so the top 400 had a tax rate of 20% or less in 2007, far lower than the marginal tax rate of 35% that the highest income earners (over $372,650) supposedly pay. It's also worth noting that only the first $106,800 of a person's income is taxed for Social Security purposes (as of 2010), so it would clearly be a boon to the Social Security Fund if everyone -- not just those making less than $106,800 -- paid the Social Security tax on their full incomes."
Who Rules America: Wealth, Income, and Power