They are from IRS data as posted on the
National Tax Payers Union website.
This IS the data. That IS the percentage of federal income taxes paid by those groups. The top 1% DID pay almost 40% of all federal income taxes collected in 2006. Other years are listed as well, and interestingly, the percentage paid by the top has gone up since 2002 (it took a significant dive from 37+% to 34-% from 2000 to 2001, then has steadily creeped up again to the highest percentage ever).
You may think they are not paying a high enough percentage of their income, which is a different debate. This ia about what percentage of federal income tax collected comes from where. The rich pays the VAST majority of federal income taxes.