“The average rate for middle-income households was projected to be 12% in 2013, the latest available data.”
The top 1% of earners, who do 99% of the complaining about tax rates, pays an average of 33%.
What percentage of people in developed countries would sign on to pay 12%? Trick question. Somewhat less than all because some (many?) would not want to accept the trade-offs of minimal taxes including worsening infrastructure, expensive health care, and tens of million in poverty.