Over the past four decades, the world’s “ultra-high-net-worth individuals” have seen their fortunes increase, after taking inflation into account, an average 7.5 percent per year. How much annually have these rich paid in taxes? They’ve been paying, Zucman calculates, an effective tax rate “equivalent to 0.3% of their wealth.” (emphasis added) A 2 percent global billionaire tax minimum would raise, Zucman calculates, as much as $250 billion a year from a mere 3,000 individuals worldwide. Extending this tax to centi-millionaires — deep pockets worth at least $100 million — would add another $140 billion annually. Raising the global billionaire minimum tax rate to 3 percent could raise the annual take to as much as $688 billion.