Federal income tax rates are highly progressive, but the total tax burden paid to all levels of government is only slightly progressive (and actually slightly regressive above the 99th percentile of income). WaPo published an article showing the total tax burden by income. The bottom 20% pay an average of 17.4%. It gradually increases to around 30% for the 80-99th percentiles then actually drops down to 29% for the top percentile. [1]

[1] https://www.washingtonpost.com/news/wonk/wp/2012/09/19/heres...