A new analysis finds the wealthiest 400 families paid a lower share of the U.S. tax burden last year than people in any other income group. The finding comes from new research by UC Berkeley economists Emmanuel Saez and Gabriel Zucman in their forthcoming book, “The Triumph of Injustice: How the Rich Dodge Taxes and How to Make Them Pay.” A dramatic animated graph of the researchers’ data produced by The New York Times shows the U.S. tax system becoming far less progressive over seven decades. In 1950, the total tax rate for the wealthiest 400 families stood at 70%; after President Trump’s tax cuts for the wealthy took effect, the tax rate on U.S. billionaires had fallen to just 23%.