From the AEO and Tax Foundation:
It's important to note for the discussion here that the US has the most progressive tax system among all OECD countries, see the Tax Foundation president Scott Hodge's article "No Country Leans on Upper-Income Households as Much as US." Specifically, the top ten percent of American households pay 45.1% of all income taxes (both personal income and payroll taxes combined), which is the highest of any of the 24 countries in the OECD and far above the 31.6% average. Adjusting for the income share of the top ten percent, the US has the highest ratio of tax share (45.1%) to income share (33.5%) for the top decile of 1.35 times, compared to the OECD average of 1.11.