We exchanged posts on this topic. The disparity of wealth is well documented.
Of course that same documentation is a comparison of population and tax............
The Tax Foundation recognizes that taxes have been reduced. And it's well documented that the wealthiest have a larger percentage of Federal Revenue. The other 99% are contributing less to the Fed Revenue because they are profiting less.
The Tax Foundation has drawn unsustainable conclusions on income! They've made the mistake of taxes/income without population migration. Instead they offer 'quintiles' which voids population numbers.
Richard Morrison, the author of your post, is the head of "TaxExemptWorld" http://www.taxexemptworld.com/ He's also the head of communications for the Tax Foundation. He's not a journalist. He's not an economist.