Richard. The point of this report is that the gap is widening exponentially.
"the wealth of billionaires had increased by 13 percent a year on average in the decade from 2006 to 2015. Last year, billionaires would have seen an uptick of $762 billion — enough to end extreme poverty seven times over."
This same sort of growth applies to the salaries at upper executive levels of major companies and governments. During this same period there has been little or no growth in the income of pensioners and blue collar and white collar workers. In other words the bulk of consumers.
It would not surprise me to see that the vast bulk of tax is paid by the majority whilst the billioners pay a minor percent of their income in taxes.
Trump's tax payments, or better lack of tax payments, would be a good example of how the very wealthy manipulate the tax rules to their advantage and pay little tax whilst at the same time increasing their wealth.