An interesting graphic showing those Americans who renounced their citizenship by year. Note the surge under Obama and the tail off when Trump took office.
Apparently the numbers are surging again ahead of the US election. 5,816 Americans have renounced their citizenship in 1H20 according to Bambridge Accountants, a 1,210% increase over the prior six months ending in December 2019. In all of calendar year 2019, 2,072 Americans handed in their citizenship.