Several sources. I'll begin with
Warren Buffett:
''It's not often you see someone stand up and say, "Tax me more!"
''Yet that's just what famed investor Warren Buffett has done in an op-ed in the New York Times headlined, "Stop Coddling the Super-Rich." Buffett says that very wealthy people like himself pay lower tax rates than the middle class, thanks to special tax categories for investment income. ''
As an example, Buffett said he paid an effective tax rate of 17.4 percent, while people who worked in his office made much less but paid higher effective tax rates of between 33 percent and 41 percent, averaging 36 percent.
"If you make money with money, as some of my super-rich friends do, your percentage may be a bit lower than mine. But if you earn money from a job, your percentage will surely exceed mine — most likely by a lot," Buffett wrote. "To understand why, you need to examine the sources of government revenue. Last year about 80 percent of these revenues came from personal income taxes and payroll taxes. The mega-rich pay income taxes at a rate of 15 percent on most of their earnings but pay practically nothing in payroll taxes. It’s a different story for the middle class: typically, they fall into the 15 percent and 25 percent income tax brackets, and then are hit with heavy payroll taxes to boot."
Key Facts
The richest 1% of Americans own 35% of the nation’s wealth. The bottom 80% own just 11% of the nation’s wealth.
In the 1950s and 1960s, when the economy was booming, the wealthiest Americans paid a top income tax rate of 91%. Today, the top rate is 43.4%.
The richest 1% pay an effective federal income tax rate of 24.7% in 2014; someone making an average of $75,000 is paying a 19.7% rate.
The average federal income tax rate of the richest 400 Americans was just 20 percent in 2009.
Taxing investment income at a much lower rate than salaries and wages are taxed loses $1.3 trillion over 10 years.
1,470 households reported income of more than $1 million in 2009 but paid zero federal income taxes on it.
CEOs of major corporations earn nearly 300 times more than an average worker.
30 percent of income inequality is due to unfair taxes and budget cuts to services and benefits.
The largest contributor to increasing income inequality has been changes in income from capital gains and dividends.
Talking points
It’s time for the wealthiest Americans and big corporations to pay their fair share of taxes. When they take unfair advantage of the many loopholes in the tax code the rest of us pick up the tab.
Instead of cutting education funding for our children, we should ask millionaires to pay a tax rate at least as high their secretary’s.
Instead of cutting Social Security and Medicare, we should ask the wealthy to give up a few tax loopholes so that we can make sure everyone has a secure retirement.
List of regions by past GDP (PPP) per capita -- France is consistently a bit behind western Europe's average, both before its revolution and after it. Also, the 
