Thank you for the question.
The Piketty, Saez and Stancheva study, published in 2011, notes a major drop in marginal tax rates in countries where that 1% has increased significantly. The correlation is clear. Even more interesting is the fact that there is no correlation between a drop in marginal tax rates and GDP growth. Consequently, the amount taxed is not related to tax levels. What is taken into consideration is the use of that money.
As for the correlation, marginal tax rates have two effects. The first is the capping of high income, as richer people have a higher savings rate. They do not spend all their money—contrary to the middle class—and they often invest their savings abroad or in the stock market. That creates an extra income and increases the growth of the richest 1%.
The second effect is that....